diff --git a/src/matrix/inversewishart.jl b/src/matrix/inversewishart.jl
index 4e9cee2ec..655e07e85 100644
--- a/src/matrix/inversewishart.jl
+++ b/src/matrix/inversewishart.jl
@@ -11,7 +11,7 @@ end
 
 #### Constructors
 
-function InverseWishart{ST<:AbstractPDMat}(df::Real, Ψ::ST)
+function InverseWishart{ST <: AbstractPDMat}(df::Real, Ψ::ST)
     p = dim(Ψ)
     df > p - 1 || error("df should be greater than dim - 1.")
     InverseWishart{ST}(df, Ψ, _invwishart_c0(df, Ψ))
@@ -35,7 +35,7 @@ insupport(d::InverseWishart, X::Matrix{Float64}) = size(X) == size(d) && isposde
 
 dim(d::InverseWishart) = dim(d.Ψ)
 size(d::InverseWishart) = (p = dim(d); (p, p))
-
+params(d::InverseWishart) = (d.df, d.Ψ, d.c0)
 
 #### Show
 
diff --git a/src/matrix/wishart.jl b/src/matrix/wishart.jl
index 934e903b7..16748df2e 100644
--- a/src/matrix/wishart.jl
+++ b/src/matrix/wishart.jl
@@ -11,7 +11,7 @@ end
 
 #### Constructors
 
-function Wishart{ST<:AbstractPDMat}(df::Real, S::ST)
+function Wishart{ST <: AbstractPDMat}(df::Real, S::ST)
     p = dim(S)
     df > p - 1 || error("df should be greater than dim - 1.")
     Wishart{ST}(df, S, _wishart_c0(df, S))
@@ -35,7 +35,7 @@ insupport(d::Wishart, X::Matrix{Float64}) = size(X) == size(d) && isposdef(X)
 
 dim(d::Wishart) = dim(d.S)
 size(d::Wishart) = (p = dim(d); (p, p))
-
+params(d::Wishart) = (d.df, d.S, d.c0)
 
 #### Show
 
diff --git a/src/mixtures/mixturemodel.jl b/src/mixtures/mixturemodel.jl
index e46b261da..abb8d8ab4 100644
--- a/src/mixtures/mixturemodel.jl
+++ b/src/mixtures/mixturemodel.jl
@@ -69,6 +69,7 @@ components(d::MixtureModel) = d.components
 component(d::MixtureModel, k::Int) = d.components[k]
 
 probs(d::MixtureModel) = probs(d.prior)
+params(d::MixtureModel) = ([params(c) for c in d.components], params(d.prior)[1])
 
 function mean(d::UnivariateMixture)
     K = ncomponents(d)
diff --git a/src/mixtures/unigmm.jl b/src/mixtures/unigmm.jl
index 307aa2be1..ce2aec2ae 100644
--- a/src/mixtures/unigmm.jl
+++ b/src/mixtures/unigmm.jl
@@ -25,6 +25,8 @@ mean(d::UnivariateGMM) = dot(d.means, probs(d))
 
 rand(d::UnivariateGMM) = (k = rand(d.prior); d.means[k] + randn() * d.stds[k])
 
+params(d::UnivariateGMM) = (d.means, d.stds, d.prior)
+
 immutable UnivariateGMMSampler <: Sampleable{Univariate,Continuous}
     means::Vector{Float64}
     stds::Vector{Float64}
diff --git a/src/multivariate/dirichlet.jl b/src/multivariate/dirichlet.jl
index cdb50fc07..6dda412d0 100644
--- a/src/multivariate/dirichlet.jl
+++ b/src/multivariate/dirichlet.jl
@@ -38,6 +38,7 @@ Base.show(io::IO, d::Dirichlet) = show(io, d, (:alpha,))
 
 length(d::Dirichlet) = length(d.alpha)
 mean(d::Dirichlet) = d.alpha .* inv(d.alpha0)
+params(d::Dirichlet) = (d.alpha,)
 
 function var(d::Dirichlet)
     α = d.alpha
diff --git a/src/multivariate/mvnormal.jl b/src/multivariate/mvnormal.jl
index a8da08525..bd6f97687 100644
--- a/src/multivariate/mvnormal.jl
+++ b/src/multivariate/mvnormal.jl
@@ -109,6 +109,7 @@ Base.show(io::IO, d::MvNormal) =
 
 length(d::MvNormal) = length(d.μ)
 mean(d::MvNormal) = convert(Vector{Float64}, d.μ)
+params(d::MvNormal) = (d.μ, d.Σ)
 
 var(d::MvNormal) = diag(d.Σ)
 cov(d::MvNormal) = full(d.Σ)
diff --git a/src/multivariate/mvnormalcanon.jl b/src/multivariate/mvnormalcanon.jl
index 17b8179c9..a8ff02e9b 100644
--- a/src/multivariate/mvnormalcanon.jl
+++ b/src/multivariate/mvnormalcanon.jl
@@ -65,6 +65,7 @@ canonform{C}(d::MvNormal{C,ZeroVector{Float64}}) = MvNormalCanon(inv(d.Σ))
 
 length(d::MvNormalCanon) = length(d.μ)
 mean(d::MvNormalCanon) = convert(Vector{Float64}, d.μ)
+params(d::MvNormalCanon) = (d.μ, d.h, d.J)
 
 var(d::MvNormalCanon) = diag(inv(d.J))
 cov(d::MvNormalCanon) = full(inv(d.J))
diff --git a/src/multivariate/mvtdist.jl b/src/multivariate/mvtdist.jl
index 58d6e141c..ec1823f4f 100644
--- a/src/multivariate/mvtdist.jl
+++ b/src/multivariate/mvtdist.jl
@@ -31,7 +31,7 @@ end
 
 function GenericMvTDist{Cov<:AbstractPDMat}(df::Float64, Σ::Cov)
     d = dim(Σ)
-    GenericMvTDist{Cov}(df, d, true, zeros(d), Σ)    
+    GenericMvTDist{Cov}(df, d, true, zeros(d), Σ)
 end
 
 ## Construction of multivariate normal with specific covariance type
@@ -80,6 +80,8 @@ invscale(d::GenericMvTDist) = full(inv(d.Σ))
 invcov(d::GenericMvTDist) = d.df>2 ? ((d.df-2)/d.df)*full(inv(d.Σ)) : NaN*ones(d.dim, d.dim)
 logdet_cov(d::GenericMvTDist) = d.df>2 ? logdet((d.df/(d.df-2))*d.Σ) : NaN
 
+params(d::GenericMvTDist) = (d.df, d.μ, d.Σ)
+
 # For entropy calculations see "Multivariate t Distributions and their Applications", S. Kotz & S. Nadarajah
 function entropy(d::GenericMvTDist)
     hdf, hdim = 0.5*d.df, 0.5*d.dim
@@ -89,12 +91,12 @@ end
 
 # evaluation (for GenericMvTDist)
 
-insupport{T<:Real}(d::AbstractMvTDist, x::AbstractVector{T}) = 
+insupport{T<:Real}(d::AbstractMvTDist, x::AbstractVector{T}) =
   length(d) == length(x) && allfinite(x)
 
-function sqmahal{T<:Real}(d::GenericMvTDist, x::DenseVector{T}) 
+function sqmahal{T<:Real}(d::GenericMvTDist, x::DenseVector{T})
     z::Vector{Float64} = d.zeromean ? x : x - d.μ
-    invquad(d.Σ, z) 
+    invquad(d.Σ, z)
 end
 
 function sqmahal!{T<:Real}(r::DenseArray, d::GenericMvTDist, x::DenseMatrix{T})
diff --git a/src/multivariate/vonmisesfisher.jl b/src/multivariate/vonmisesfisher.jl
index 35ab5cb9c..07c2c4e66 100644
--- a/src/multivariate/vonmisesfisher.jl
+++ b/src/multivariate/vonmisesfisher.jl
@@ -42,7 +42,7 @@ meandir(d::VonMisesFisher) = d.μ
 concentration(d::VonMisesFisher) = d.κ
 
 insupport{T<:Real}(d::VonMisesFisher, x::DenseVector{T}) = isunitvec(x)
-
+params(d::VonMisesFisher) = (d.μ, d.κ)
 
 ### Evaluation
 
@@ -51,13 +51,13 @@ function _vmflck(p, κ)
     q = hp - 1.0
     q * log(κ) - hp * log(2π) - log(besseli(q, κ))
 end
-_vmflck3(κ) = log(κ) - log2π - κ - log1mexp(-2.0 * κ) 
+_vmflck3(κ) = log(κ) - log2π - κ - log1mexp(-2.0 * κ)
 vmflck(p, κ) = (p == 3 ? _vmflck3(κ) : _vmflck(p, κ))::Float64
 
 _logpdf{T<:Real}(d::VonMisesFisher, x::DenseVector{T}) = d.logCκ + d.κ * dot(d.μ, x)
 
 
-### Sampling 
+### Sampling
 
 sampler(d::VonMisesFisher) = VonMisesFisherSampler(d.μ, d.κ)
 
@@ -106,6 +106,4 @@ function _vmf_estkappa(p::Int, ρ::Float64)
     return κ
 end
 
-_vmfA(half_p::Float64, κ::Float64) = besseli(half_p, κ) / besseli(half_p - 1.0, κ) 
-
-
+_vmfA(half_p::Float64, κ::Float64) = besseli(half_p, κ) / besseli(half_p - 1.0, κ)
diff --git a/src/testutils.jl b/src/testutils.jl
index d394dae93..0caf7451a 100644
--- a/src/testutils.jl
+++ b/src/testutils.jl
@@ -35,6 +35,7 @@ function test_distr(distr::DiscreteUnivariateDistribution, n::Int)
 
     test_stats(distr, vs)
     test_samples(distr, n)
+    test_params(distr)
 end
 
 
@@ -50,6 +51,7 @@ function test_distr(distr::ContinuousUnivariateDistribution, n::Int)
 
     xs = test_samples(distr, n)
     allow_test_stats(distr) && test_stats(distr, xs)
+    test_params(distr)
 end
 
 
@@ -505,3 +507,22 @@ function test_stats(d::ContinuousUnivariateDistribution, xs::AbstractVector{Floa
         end
     end
 end
+
+function test_params(d::Distribution)
+    # simply test that params returns something sufficient to
+    # reconstruct d
+    D = typeof(d)
+    pars = params(d)
+    d_new = D(pars...)
+    @test d_new == d
+end
+
+function test_params(d::Truncated)
+    # simply test that params returns something sufficient to
+    # reconstruct d
+    d_unt = d.untruncated
+    D = typeof(d_unt)
+    pars = params(d_unt)
+    d_new = Truncated(D(pars...), d.lower, d.upper)
+    @test d_new == d
+end
diff --git a/src/univariate/discrete/noncentralhypergeometric.jl b/src/univariate/discrete/noncentralhypergeometric.jl
index bfee2f00e..e28945637 100644
--- a/src/univariate/discrete/noncentralhypergeometric.jl
+++ b/src/univariate/discrete/noncentralhypergeometric.jl
@@ -32,6 +32,8 @@ function quantile(d::NoncentralHypergeometric, q::Float64)
     end
 end
 
+params(d::NoncentralHypergeometric) = (d.ns, d.nf, d.n, d.ω)
+
 ## Fisher's noncentral hypergeometric distribution
 
 immutable FisherNoncentralHypergeometric <: NoncentralHypergeometric
diff --git a/test/dirichlet.jl b/test/dirichlet.jl
index 89e6fdbf1..bd5e85b55 100644
--- a/test/dirichlet.jl
+++ b/test/dirichlet.jl
@@ -35,6 +35,7 @@ d = Dirichlet(v)
 @test length(d) == length(v)
 @test d.alpha == v
 @test d.alpha0 == sum(v)
+@test d == typeof(d)(params(d)...)
 
 @test_approx_eq mean(d) v / sum(v)
 @test_approx_eq cov(d) [8 -2 -6; -2 5 -3; -6 -3 9] / (36 * 7)
diff --git a/test/matrix.jl b/test/matrix.jl
index dd51c641c..91b333622 100644
--- a/test/matrix.jl
+++ b/test/matrix.jl
@@ -11,6 +11,7 @@ IW = InverseWishart(v,S)
 for d in [W,IW]
     @test size(d) == size(rand(d))
     @test length(d) == length(rand(d))
+    @test typeof(d)(params(d)...) == d
 end
 
 @test_approx_eq_eps mean(rand(W,100000)) mean(W) 0.1
diff --git a/test/mixture.jl b/test/mixture.jl
index 198cfbeed..389463045 100644
--- a/test/mixture.jl
+++ b/test/mixture.jl
@@ -121,7 +121,19 @@ function test_mixture(g::MultivariateMixture, n::Int, ns::Int)
     @test_approx_eq_eps cov(Xs, vardim=2) cov(g) 0.01
 end
 
+function test_params(g::AbstractMixtureModel)
+    C = eltype(g.components)
+    pars = params(g)
+    mm = MixtureModel(C, pars...)
+    @test g.prior == mm.prior
+    @test g.components == mm.components
+end
 
+function test_params(g::UnivariateGMM)
+    pars = params(g)
+    mm = UnivariateGMM(pars...)
+    @test g == mm
+end
 
 # Tests
 
@@ -131,11 +143,13 @@ g_u = MixtureModel(Normal, [(0.0, 1.0), (2.0, 1.0), (-4.0, 1.5)], [0.2, 0.5, 0.3
 @test isa(g_u, MixtureModel{Univariate, Continuous, Normal})
 @test ncomponents(g_u) == 3
 test_mixture(g_u, 1000, 10^6)
+test_params(g_u)
 
 g_u = UnivariateGMM([0.0, 2.0, -4.0], [1.0, 1.2, 1.5], Categorical([0.2, 0.5, 0.3]))
 @test isa(g_u, UnivariateGMM)
 @test ncomponents(g_u) == 3
 test_mixture(g_u, 1000, 10^6)
+test_params(g_u)
 
 println("    testing MultivariateMixture")
 g_m = MixtureModel(
@@ -147,3 +161,4 @@ g_m = MixtureModel(
 @test length(components(g_m)) == 3
 @test length(g_m) == 2
 test_mixture(g_m, 1000, 10^6)
+test_params(g_m)
diff --git a/test/multinomial.jl b/test/multinomial.jl
index e9f282c80..61190108f 100644
--- a/test/multinomial.jl
+++ b/test/multinomial.jl
@@ -26,6 +26,7 @@ x = rand(d)
 @test insupport(d, x)
 @test size(x) == size(d)
 @test length(x) == length(d)
+@test d == typeof(d)(params(d)...)
 
 x = rand(d, 100)
 @test isa(x, Matrix{Int})
@@ -86,4 +87,3 @@ r = fit_mle(Multinomial, x, fill(2.0, size(x,2)))
 @test r.n == nt
 @test length(r) == length(p)
 @test_approx_eq_eps probs(r) p 0.02
-
diff --git a/test/mvnormal.jl b/test/mvnormal.jl
index 6f602038a..46415db94 100644
--- a/test/mvnormal.jl
+++ b/test/mvnormal.jl
@@ -11,7 +11,7 @@ import Distributions: distrname
 
 function test_mvnormal(g::AbstractMvNormal, n_tsamples::Int=10^6)
     d = length(g)
-    μ = mean(g) 
+    μ = mean(g)
     Σ = cov(g)
     @test isa(μ, Vector{Float64})
     @test isa(Σ, Matrix{Float64})
@@ -22,6 +22,7 @@ function test_mvnormal(g::AbstractMvNormal, n_tsamples::Int=10^6)
     ldcov = logdetcov(g)
     @test_approx_eq ldcov logdet(Σ)
     vs = diag(Σ)
+    @test g == typeof(g)(params(g)...)
 
     # sampling
     X = rand(g, n_tsamples)
@@ -61,18 +62,18 @@ h = [1., 2., 3.]
 dv = [1.2, 3.4, 2.6]
 J = [4. -2. -1.; -2. 5. -1.; -1. -1. 6.]
 
-for (T, g, μ, Σ) in [ 
-    (IsoNormal, MvNormal(mu, sqrt(2.0)), mu, 2.0 * eye(3)), 
-    (ZeroMeanIsoNormal, MvNormal(3, sqrt(2.0)), zeros(3), 2.0 * eye(3)), 
-    (DiagNormal, MvNormal(mu, sqrt(va)), mu, diagm(va)), 
-    (ZeroMeanDiagNormal, MvNormal(sqrt(va)), zeros(3), diagm(va)), 
-    (FullNormal, MvNormal(mu, C), mu, C), 
+for (T, g, μ, Σ) in [
+    (IsoNormal, MvNormal(mu, sqrt(2.0)), mu, 2.0 * eye(3)),
+    (ZeroMeanIsoNormal, MvNormal(3, sqrt(2.0)), zeros(3), 2.0 * eye(3)),
+    (DiagNormal, MvNormal(mu, sqrt(va)), mu, diagm(va)),
+    (ZeroMeanDiagNormal, MvNormal(sqrt(va)), zeros(3), diagm(va)),
+    (FullNormal, MvNormal(mu, C), mu, C),
     (ZeroMeanFullNormal, MvNormal(C), zeros(3), C),
     (IsoNormalCanon, MvNormalCanon(h, 2.0), h / 2.0, 0.5 * eye(3)),
     (ZeroMeanIsoNormalCanon, MvNormalCanon(3, 2.0), zeros(3), 0.5 * eye(3)),
     (DiagNormalCanon, MvNormalCanon(h, dv), h ./ dv, diagm(1.0 ./ dv)),
     (ZeroMeanDiagNormalCanon, MvNormalCanon(dv), zeros(3), diagm(1.0 ./ dv)),
-    (FullNormalCanon, MvNormalCanon(h, J), J \ h, inv(J)), 
+    (FullNormalCanon, MvNormalCanon(h, J), J \ h, inv(J)),
     (ZeroMeanFullNormalCanon, MvNormalCanon(J), zeros(3), inv(J)) ]
 
     println("    testing $(distrname(g))")
@@ -80,16 +81,16 @@ for (T, g, μ, Σ) in [
     @test isa(g, T)
     @test_approx_eq mean(g) μ
     @test_approx_eq cov(g) Σ
-    test_mvnormal(g) 
+    test_mvnormal(g)
 
     # conversion between mean form and canonical form
     if isa(g, MvNormal)
-        gc = canonform(g) 
+        gc = canonform(g)
         @test isa(gc, MvNormalCanon)
         @test length(gc) == length(g)
         @test_approx_eq mean(gc) mean(g)
         @test_approx_eq cov(gc) cov(g)
-    else 
+    else
         @assert isa(g, MvNormalCanon)
         gc = meanform(g)
         @test isa(gc, MvNormal)
@@ -116,7 +117,7 @@ function _gauss_mle(x::Matrix{Float64}, w::Vector{Float64})
     mu = (x * w) * (1/sw)
     z = x .- mu
     C = (z * scale(w, z')) * (1/sw)
-    Base.LinAlg.copytri!(C, 'U') 
+    Base.LinAlg.copytri!(C, 'U')
     return mu, C
 end
 
@@ -161,5 +162,3 @@ g = fit_mle(DiagNormal, x, w)
 @test isa(g, DiagNormal)
 @test_approx_eq g.μ uw
 @test_approx_eq g.Σ.diag diag(Cw)
-
-
diff --git a/test/mvtdist.jl b/test/mvtdist.jl
index ed4973f86..fcd08962c 100644
--- a/test/mvtdist.jl
+++ b/test/mvtdist.jl
@@ -23,4 +23,5 @@ df = [1., 2, 3, 5, 10]
 for i = 1:length(df)
   d = MvTDist(df[i], mu, Sigma)
   @test_approx_eq_eps logpdf(d, [-2., 3]) rvalues[i] 1.0e-8
+  @test d == typeof(d)(params(d)...)
 end
diff --git a/test/noncentralhypergeometric.jl b/test/noncentralhypergeometric.jl
index dc7bdd0db..f694d0c6a 100644
--- a/test/noncentralhypergeometric.jl
+++ b/test/noncentralhypergeometric.jl
@@ -9,6 +9,7 @@ n = 100
 # http://en.wikipedia.org/wiki/Fisher's_noncentral_hypergeometric_distribution
 ω = 10.0
 d = FisherNoncentralHypergeometric(ns, nf, n, ω)
+@test d == typeof(d)(params(d)...)
 
 @test_approx_eq_eps mean(d) 71.95759 1e-5
 @test mode(d) == 72
@@ -50,6 +51,7 @@ n = 100
 # http://en.wikipedia.org/wiki/Fisher's_noncentral_hypergeometric_distribution
 ω = 10.0
 d = WalleniusNoncentralHypergeometric(ns, nf, n, ω)
+@test d == typeof(d)(params(d)...)
 
 @test_approx_eq_eps mean(d) 78.82945 1e-5
 @test mode(d) == 80
@@ -81,4 +83,4 @@ ref = Hypergeometric(ns,nf,n)
 @test_approx_eq_eps cdf(d, 51) cdf(ref, 51) 1e-7
 @test_approx_eq_eps quantile(d, 0.05) quantile(ref, 0.05) 1e-7
 @test_approx_eq_eps quantile(d, 0.95) quantile(ref, 0.95) 1e-7
-@test mode(d) == mode(ref)
\ No newline at end of file
+@test mode(d) == mode(ref)
diff --git a/test/vonmisesfisher.jl b/test/vonmisesfisher.jl
index c01a2b439..8ffda1db0 100644
--- a/test/vonmisesfisher.jl
+++ b/test/vonmisesfisher.jl
@@ -23,6 +23,7 @@ function test_vonmisesfisher(p::Int, κ::Float64, n::Int, ns::Int)
     @test length(d) == p
     @test meandir(d) == μ
     @test concentration(d) == κ
+    @test d == typeof(d)(params(d)...)
     # println(d)
 
     θ = κ * μ
@@ -72,4 +73,3 @@ for (p, κ) in [(2, 1.0),
 
     test_vonmisesfisher(p, κ, n, ns)
 end
-