diff --git a/Cargo.toml b/Cargo.toml
index 3abc682..a59ad0e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,6 +18,8 @@ triomphe = "0.1.5"
 typenum = "1.14.0"
 vec_map = "0.8.2"
 smallvec = "1.8.0"
+arbitrary = { version = "1.2.3", features = ["derive"] }
+ethereum-types = { version = "0.14.1", features = ["arbitrary"] }
 
 [dev-dependencies]
 ssz_types = "0.5.0"
diff --git a/src/interface.rs b/src/interface.rs
index 1ec7c0c..4ecb7f3 100644
--- a/src/interface.rs
+++ b/src/interface.rs
@@ -5,6 +5,7 @@ use crate::{
     iter::Iter,
     Cow, Error,
 };
+use arbitrary::Arbitrary;
 use std::collections::BTreeMap;
 use std::marker::PhantomData;
 use tree_hash::{Hash256, TreeHash};
@@ -37,7 +38,7 @@ where
     ) -> Result<(), Error>;
 }
 
-#[derive(Debug, PartialEq, Clone)]
+#[derive(Debug, PartialEq, Clone, Arbitrary)]
 pub struct Interface<T, B, U>
 where
     T: TreeHash + Clone,
diff --git a/src/leaf.rs b/src/leaf.rs
index 709f59b..bd64bfe 100644
--- a/src/leaf.rs
+++ b/src/leaf.rs
@@ -1,13 +1,19 @@
-use crate::Arc;
+use crate::{
+    utils::{arb_arc, arb_rwlock},
+    Arc,
+};
+use arbitrary::Arbitrary;
 use derivative::Derivative;
 use parking_lot::RwLock;
 use tree_hash::Hash256;
 
-#[derive(Debug, Derivative)]
+#[derive(Debug, Derivative, Arbitrary)]
 #[derivative(PartialEq, Hash)]
 pub struct Leaf<T> {
     #[derivative(PartialEq = "ignore", Hash = "ignore")]
+    #[arbitrary(with = arb_rwlock)]
     pub hash: RwLock<Hash256>,
+    #[arbitrary(with = arb_arc)]
     pub value: Arc<T>,
 }
 
diff --git a/src/list.rs b/src/list.rs
index e8dc47b..7a8faae 100644
--- a/src/list.rs
+++ b/src/list.rs
@@ -4,8 +4,9 @@ use crate::interface_iter::{InterfaceIter, InterfaceIterCow};
 use crate::iter::Iter;
 use crate::serde::ListVisitor;
 use crate::update_map::MaxMap;
-use crate::utils::{int_log, opt_packing_depth, updated_length, Length};
+use crate::utils::{arb_arc, int_log, opt_packing_depth, updated_length, Length};
 use crate::{Arc, Cow, Error, Tree, UpdateMap};
+use arbitrary::Arbitrary;
 use derivative::Derivative;
 use itertools::process_results;
 use serde::{ser::SerializeSeq, Deserialize, Deserializer, Serialize, Serializer};
@@ -16,20 +17,25 @@ use tree_hash::{Hash256, PackedEncoding, TreeHash};
 use typenum::Unsigned;
 use vec_map::VecMap;
 
-#[derive(Debug, Clone, Derivative)]
+#[derive(Debug, Clone, Derivative, Arbitrary)]
 #[derivative(PartialEq(
     bound = "T: TreeHash + PartialEq + Clone, N: Unsigned, U: UpdateMap<T> + PartialEq"
 ))]
+#[arbitrary(bound = "T: Arbitrary<'arbitrary> + TreeHash + PartialEq + Clone")]
+#[arbitrary(bound = "N: Unsigned, U: Arbitrary<'arbitrary> + UpdateMap<T> + PartialEq")]
 pub struct List<T: TreeHash + Clone, N: Unsigned, U: UpdateMap<T> = MaxMap<VecMap<T>>> {
     pub(crate) interface: Interface<T, ListInner<T, N>, U>,
 }
 
-#[derive(Debug, Clone, Derivative)]
+#[derive(Debug, Clone, Derivative, Arbitrary)]
 #[derivative(PartialEq(bound = "T: TreeHash + PartialEq + Clone, N: Unsigned"))]
+#[arbitrary(bound = "T: Arbitrary<'arbitrary> + TreeHash + PartialEq + Clone, N: Unsigned")]
 pub struct ListInner<T: TreeHash + Clone, N: Unsigned> {
+    #[arbitrary(with = arb_arc)]
     pub(crate) tree: Arc<Tree<T>>,
     pub(crate) length: Length,
     pub(crate) depth: usize,
+    #[arbitrary(default)]
     _phantom: PhantomData<N>,
 }
 
diff --git a/src/packed_leaf.rs b/src/packed_leaf.rs
index 0862fbf..b0f3770 100644
--- a/src/packed_leaf.rs
+++ b/src/packed_leaf.rs
@@ -1,13 +1,15 @@
-use crate::{Error, UpdateMap};
+use crate::{utils::arb_rwlock, Error, UpdateMap};
+use arbitrary::Arbitrary;
 use derivative::Derivative;
 use parking_lot::RwLock;
 use std::ops::ControlFlow;
 use tree_hash::{Hash256, TreeHash, BYTES_PER_CHUNK};
 
-#[derive(Debug, Derivative)]
+#[derive(Debug, Derivative, Arbitrary)]
 #[derivative(PartialEq, Hash)]
 pub struct PackedLeaf<T: TreeHash + Clone> {
     #[derivative(PartialEq = "ignore", Hash = "ignore")]
+    #[arbitrary(with = arb_rwlock)]
     pub hash: RwLock<Hash256>,
     pub(crate) values: Vec<T>,
 }
diff --git a/src/tree.rs b/src/tree.rs
index 31bc0b0..5b99058 100644
--- a/src/tree.rs
+++ b/src/tree.rs
@@ -1,5 +1,6 @@
-use crate::utils::{opt_hash, opt_packing_depth, opt_packing_factor};
+use crate::utils::{arb_arc, arb_rwlock, opt_hash, opt_packing_depth, opt_packing_factor};
 use crate::{Arc, Error, Leaf, PackedLeaf, UpdateMap};
+use arbitrary::Arbitrary;
 use derivative::Derivative;
 use ethereum_hashing::{hash32_concat, ZERO_HASHES};
 use parking_lot::RwLock;
@@ -10,15 +11,18 @@ use std::collections::BTreeMap;
 use std::ops::ControlFlow;
 use tree_hash::{Hash256, TreeHash};
 
-#[derive(Debug, Derivative)]
+#[derive(Debug, Derivative, Arbitrary)]
 #[derivative(PartialEq, Hash)]
 pub enum Tree<T: TreeHash + Clone> {
     Leaf(Leaf<T>),
     PackedLeaf(PackedLeaf<T>),
     Node {
         #[derivative(PartialEq = "ignore", Hash = "ignore")]
+        #[arbitrary(with = arb_rwlock)]
         hash: RwLock<Hash256>,
+        #[arbitrary(with = arb_arc)]
         left: Arc<Self>,
+        #[arbitrary(with = arb_arc)]
         right: Arc<Self>,
     },
     Zero(usize),
diff --git a/src/update_map.rs b/src/update_map.rs
index 827bb5d..eb7ea4a 100644
--- a/src/update_map.rs
+++ b/src/update_map.rs
@@ -1,5 +1,6 @@
 use crate::cow::{BTreeCow, Cow, VecCow};
 use crate::utils::max_btree_index;
+use arbitrary::Arbitrary;
 use std::collections::{btree_map::Entry, BTreeMap};
 use std::ops::ControlFlow;
 use vec_map::VecMap;
@@ -162,8 +163,10 @@ impl<T: Clone> UpdateMap<T> for VecMap<T> {
     }
 }
 
-#[derive(Debug, Default, Clone, PartialEq)]
+#[derive(Debug, Default, Clone, PartialEq, Arbitrary)]
+#[arbitrary(bound = "M: Default")]
 pub struct MaxMap<M> {
+    #[arbitrary(default)]
     inner: M,
     max_key: usize,
 }
diff --git a/src/utils.rs b/src/utils.rs
index 943c7ff..eeef206 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -1,9 +1,11 @@
-use crate::UpdateMap;
+use crate::{Arc, UpdateMap};
+use arbitrary::Arbitrary;
+use parking_lot::RwLock;
 use std::collections::BTreeMap;
 use tree_hash::{Hash256, TreeHash, TreeHashType};
 
 /// Length type, to avoid confusion with depth and other `usize` parameters.
-#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone, Copy)]
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Arbitrary)]
 pub struct Length(pub usize);
 
 impl Length {
@@ -60,3 +62,15 @@ pub fn opt_hash(
 ) -> Option<Hash256> {
     hashes?.get(&(depth, prefix)).copied()
 }
+
+pub fn arb_arc<'a, T: Arbitrary<'a>>(
+    u: &mut arbitrary::Unstructured<'a>,
+) -> arbitrary::Result<Arc<T>> {
+    T::arbitrary(u).map(Arc::new)
+}
+
+pub fn arb_rwlock<'a, T: Arbitrary<'a>>(
+    u: &mut arbitrary::Unstructured<'a>,
+) -> arbitrary::Result<RwLock<T>> {
+    T::arbitrary(u).map(RwLock::new)
+}
diff --git a/src/vector.rs b/src/vector.rs
index 3d080a1..cce220d 100644
--- a/src/vector.rs
+++ b/src/vector.rs
@@ -2,8 +2,9 @@ use crate::interface::{ImmList, Interface, MutList};
 use crate::interface_iter::InterfaceIter;
 use crate::iter::Iter;
 use crate::update_map::MaxMap;
-use crate::utils::Length;
+use crate::utils::{arb_arc, Length};
 use crate::{Arc, Cow, Error, List, Tree, UpdateMap};
+use arbitrary::Arbitrary;
 use derivative::Derivative;
 use serde::{Deserialize, Serialize};
 use ssz::{Decode, Encode, SszEncoder, TryFromIter, BYTES_PER_LENGTH_OFFSET};
@@ -14,7 +15,7 @@ use tree_hash::{Hash256, PackedEncoding, TreeHash};
 use typenum::Unsigned;
 use vec_map::VecMap;
 
-#[derive(Debug, Derivative, Clone, Serialize, Deserialize)]
+#[derive(Debug, Derivative, Clone, Serialize, Deserialize, Arbitrary)]
 #[derivative(PartialEq(
     bound = "T: TreeHash + Clone + PartialEq, N: Unsigned, U: UpdateMap<T> + PartialEq"
 ))]
@@ -24,15 +25,20 @@ use vec_map::VecMap;
 #[serde(bound(
     deserialize = "T: TreeHash + Clone + Deserialize<'de>, N: Unsigned, U: UpdateMap<T>"
 ))]
+#[arbitrary(bound = "T: Arbitrary<'arbitrary> + TreeHash + Clone")]
+#[arbitrary(bound = "N: Unsigned, U: Arbitrary<'arbitrary> + UpdateMap<T>")]
 pub struct Vector<T: TreeHash + Clone, N: Unsigned, U: UpdateMap<T> = MaxMap<VecMap<T>>> {
     pub(crate) interface: Interface<T, VectorInner<T, N>, U>,
 }
 
-#[derive(Debug, Derivative, Clone)]
+#[derive(Debug, Derivative, Clone, Arbitrary)]
 #[derivative(PartialEq(bound = "T: TreeHash + Clone + PartialEq, N: Unsigned"))]
+#[arbitrary(bound = "T: Arbitrary<'arbitrary> + TreeHash + Clone, N: Unsigned")]
 pub struct VectorInner<T: TreeHash + Clone, N: Unsigned> {
+    #[arbitrary(with = arb_arc)]
     pub(crate) tree: Arc<Tree<T>>,
     pub(crate) depth: usize,
+    #[arbitrary(default)]
     _phantom: PhantomData<N>,
 }