diff --git a/src/Domain.js b/src/Domain.js
index 3651912..9371c8d 100644
--- a/src/Domain.js
+++ b/src/Domain.js
@@ -199,6 +199,9 @@ EIP712Domain.fromSignatureRequest = function fromSignatureRequest(request) {
   const dfs = type => {
     for (const {type: subtype} of types[type]) {
       if (marked.has(subtype) || isNotStructureType(subtype)) continue
+      if (isArrayType(subtype)){
+        subtype = subtype.substring(0,subtype.indexOf("["))
+      }
       if (cyclecheck.has(subtype)) {
         throw new Error('Cannot construct domain from signature request with cyclic dependencies')
       }
diff --git a/src/Type.js b/src/Type.js
index b500a10..a6b7231 100644
--- a/src/Type.js
+++ b/src/Type.js
@@ -120,6 +120,24 @@ export default function Type (primaryType, defs) {
       }
     }
 
+    encodeField(type, value){
+      if (isDynamicType(type)){
+        return {type:'bytes32', value:Buffer.from(keccak256(value), 'hex')}
+      } else if (type in domain.types){
+        // Structure Types are recursively encoded and hashed
+        return {type:"bytes32", value: Buffer.from(keccak256(value.encodeData()), 'hex')}
+      } else if (isArrayType(type)){
+        // Array types are the hash of their encoded members concatenated
+        var innerType = type.slice(0, type.lastIndexOf('['));
+        var encodedValues = value.map(item => this.encodeField(innerType, item));
+        return {type:'bytes32', value: Buffer.from(keccak256(abi.rawEncode(encodedValues.map(v=>v.type), encodedValues.map(v=>v.value))), 'hex')}
+      } else if (isAtomicType(type)){
+        return {type: type, value:value}
+      } else {
+        throw new Error(`Unknown type: ${type}`)
+      }
+    }
+
     /**
      * @override
      * Return the EIP712 data encoding of this instance, padding each member
@@ -135,24 +153,9 @@ export default function Type (primaryType, defs) {
       let values = [Buffer.from(this.constructor.typeHash(), 'hex')]
 
       for (const {type, name} of this.constructor.properties) {
-        if (isDynamicType(type)) {
-          // Dynamic types are hashed
-          types.push('bytes32')
-          values.push(Buffer.from(keccak256(this[name]), 'hex'))
-        } else if (type in domain.types) {
-          // Structure Types are recursively encoded and hashed
-          types.push('bytes32')
-          values.push(Buffer.from(keccak256(this[name].encodeData()), 'hex'))
-        } else if (isArrayType(type)) {
-          // TODO: Figure out the spec for encoding array types
-          throw new Error('[DEV] Array types not yet supported')
-        } else if (isAtomicType(type)) {
-          // Atomic types have their encoding defined by the solidity ABI
-          types.push(type)
-          values.push(this[name])
-        } else {
-          throw new Error(`Unknown type: ${type}`)
-        }
+        var {type:t,value:v} = this.encodeField(type, this[name])
+        types.push(t)
+        values.push(v)
       }
 
       return abi.rawEncode(types, values)
@@ -227,6 +230,11 @@ function validateTypeDefinition({name, type}, domain) {
   if (typeof type === 'object') {
     // TODO: Allow recursive type defintions?
     throw new Error('Nested type definitions not supported')
+  } else if (isArrayType(type)){
+    var primitiveType = type.substring(0, type.lastIndexOf("["));
+    if (!primitiveType in domain.types){
+      throw new Error(`Type ${primitiveType} is undefined in this domain`)
+    }
   } else if (!isPrimitiveType(type) && !(type in domain.types)) {
     // Refuse undefined, non-primitive types
     throw new Error(`Type ${type} is undefined in this domain`)
@@ -246,9 +254,15 @@ function validateTypeDefinition({name, type}, domain) {
 function findDependencies(props, domain, found=[]) {
   for (let {type} of props) {
     if (isPrimitiveType(type)) continue
+    var dependentTypeName = type
+    if (isArrayType(type)){
+      dependentTypeName = type.substring(0, type.lastIndexOf("["));
+      if (isPrimitiveType(dependentTypeName)) continue
+    }
+
     // Merge the found array with new dependencies of 
     found = found.concat(
-      [type, ...findDependencies(domain.types[type].properties, domain, found)]
+      [dependentTypeName, ...findDependencies(domain.types[dependentTypeName].properties, domain, found)]
         .filter(t => !found.includes(t))
     )
   }
diff --git a/src/__tests__/data/Mail.json b/src/__tests__/data/Mail.json
index e712cf8..5d6a413 100644
--- a/src/__tests__/data/Mail.json
+++ b/src/__tests__/data/Mail.json
@@ -13,7 +13,7 @@
         ],
         "Mail": [
             { "name": "from", "type": "Person" },
-            { "name": "to", "type": "Person" },
+            { "name": "to", "type": "Person[]" },
             { "name": "contents", "type": "string" }
         ]
     },
@@ -29,20 +29,20 @@
             "name": "Cow",
             "wallet": "0xCD2a3d9F938E13CD947Ec05AbC7FE734Df8DD826"
         },
-        "to": {
+        "to": [{
             "name": "Bob",
             "wallet": "0xbBbBBBBbbBBBbbbBbbBbbbbBBbBbbbbBbBbbBBbB"
-        },
+        }],
         "contents": "Hello, Bob!"
     }
   },
   "results": {
     "Mail": {
-      "encodeType": "Mail(Person from,Person to,string contents)Person(string name,address wallet)",
-      "typeHash": "0xa0cedeb2dc280ba39b857546d74f5549c3a1d7bdc2dd96bf881f76108e23dac2",
-      "encodeData": "0xa0cedeb2dc280ba39b857546d74f5549c3a1d7bdc2dd96bf881f76108e23dac2fc71e5fa27ff56c350aa531bc129ebdf613b772b6604664f5d8dbe21b85eb0c8cd54f074a4af31b4411ff6a60c9719dbd559c221c8ac3492d9d872b041d703d1b5aadf3154a261abdd9086fc627b61efca26ae5702701d05cd2305f7c52a2fc8",
-      "hashStruct": "0xc52c0ee5d84264471806290a3f2c4cecfc5490626bf912d01f240d7a274b371e",
-      "signHash": "0xbe609aee343fb3c4b28e1df9e632fca64fcfaede20f02e86244efddf30957bd2"
+      "encodeType": "Mail(Person from,Person[] to,string contents)Person(string name,address wallet)",
+      "typeHash": "0xdd57d9596af52b430ced3d5b52d4e3d5dccfdf3e0572db1dcf526baad311fbd1",
+      "encodeData": "0xdd57d9596af52b430ced3d5b52d4e3d5dccfdf3e0572db1dcf526baad311fbd1fc71e5fa27ff56c350aa531bc129ebdf613b772b6604664f5d8dbe21b85eb0c8e2ec7c01837071382eadbfdffa6c4c47de741fa0fda906874da49c4192dbe6edb5aadf3154a261abdd9086fc627b61efca26ae5702701d05cd2305f7c52a2fc8",
+      "hashStruct": "0xb737d8ce302eba53138b4a278391f7174db4fe0efb501e813572ee339d5e7751",
+      "signHash": "0xe3e147d255f92f5a9de155defefb2816b1ca970e975b38baadb0cca27e733d36"
     },
     "domainSeparator": "0xf2cee375fa42b42143804025fc449deafd50cc031ca257e0b194a650a912090f"
   }