diff --git a/Tests/Recurly/Purchase_Test.php b/Tests/Recurly/Purchase_Test.php
index 338b1514..fafb7ec4 100644
--- a/Tests/Recurly/Purchase_Test.php
+++ b/Tests/Recurly/Purchase_Test.php
@@ -53,6 +53,7 @@ public function mockPurchase() {
     $adjustment->currency = 'USD';
     $adjustment->quantity = 1;
     $adjustment->revenue_schedule_type = 'at_invoice';
+    $adjustment->custom_fields[] = new Recurly_CustomField('size', 'small');
 
     $purchase->adjustments[] = $adjustment;
 
@@ -63,7 +64,7 @@ public function testXml() {
     $purchase = $this->mockPurchase();
 
     $this->assertEquals(
-      "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n<purchase><account><account_code>aba9209a-aa61-4790-8e61-0a2692435fee</account_code><billing_info><token_id>7z6furn4jvb9</token_id></billing_info><address><address1>123 Main St.</address1><city>San Francisco</city><state>CA</state><zip>94110</zip><country>US</country><phone>555-555-5555</phone></address><dunning_campaign_id>1234abcd</dunning_campaign_id></account><adjustments><adjustment><currency>USD</currency><unit_amount_in_cents>1000</unit_amount_in_cents><quantity>1</quantity><revenue_schedule_type>at_invoice</revenue_schedule_type><product_code>abcd123</product_code></adjustment></adjustments><collection_method>automatic</collection_method><currency>USD</currency><customer_notes>Customer Notes</customer_notes><terms_and_conditions>Terms and Conditions</terms_and_conditions><vat_reverse_charge_notes>VAT Reverse Charge Notes</vat_reverse_charge_notes><shipping_address><address1>400 Dolores St</address1><city>San Francisco</city><state>CA</state><zip>94110</zip><country>US</country><nickname>Home</nickname><first_name>Dolores</first_name><last_name>Du Monde</last_name></shipping_address><gateway_code>aBcD1234</gateway_code><transaction_type>moto</transaction_type></purchase>\n",
+      "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n<purchase><account><account_code>aba9209a-aa61-4790-8e61-0a2692435fee</account_code><billing_info><token_id>7z6furn4jvb9</token_id></billing_info><address><address1>123 Main St.</address1><city>San Francisco</city><state>CA</state><zip>94110</zip><country>US</country><phone>555-555-5555</phone></address><dunning_campaign_id>1234abcd</dunning_campaign_id></account><adjustments><adjustment><currency>USD</currency><unit_amount_in_cents>1000</unit_amount_in_cents><quantity>1</quantity><revenue_schedule_type>at_invoice</revenue_schedule_type><product_code>abcd123</product_code><custom_fields><custom_field><name>size</name><value>small</value></custom_field></custom_fields></adjustment></adjustments><collection_method>automatic</collection_method><currency>USD</currency><customer_notes>Customer Notes</customer_notes><terms_and_conditions>Terms and Conditions</terms_and_conditions><vat_reverse_charge_notes>VAT Reverse Charge Notes</vat_reverse_charge_notes><shipping_address><address1>400 Dolores St</address1><city>San Francisco</city><state>CA</state><zip>94110</zip><country>US</country><nickname>Home</nickname><first_name>Dolores</first_name><last_name>Du Monde</last_name></shipping_address><gateway_code>aBcD1234</gateway_code><transaction_type>moto</transaction_type></purchase>\n",
       $purchase->xml()
     );
   }
diff --git a/Tests/fixtures/adjustments/show-200.xml b/Tests/fixtures/adjustments/show-200.xml
index 78cae3a2..b509ac53 100644
--- a/Tests/fixtures/adjustments/show-200.xml
+++ b/Tests/fixtures/adjustments/show-200.xml
@@ -12,6 +12,12 @@ Content-Type: application/xml; charset=utf-8
   <description>$12 Annual Subscription</description>
   <accounting_code></accounting_code>
   <product_code nil="nil"></product_code>
+  <custom_fields type="array">
+    <custom_field>
+      <name>size</name>
+      <value>small</value>
+    </custom_field>
+  </custom_fields>
   <origin>plan</origin>
   <unit_amount_in_cents type="integer">1200</unit_amount_in_cents>
   <quantity type="integer">1</quantity>
diff --git a/Tests/fixtures/purchases/authorize-200.xml b/Tests/fixtures/purchases/authorize-200.xml
index ca2b8699..7f01701e 100644
--- a/Tests/fixtures/purchases/authorize-200.xml
+++ b/Tests/fixtures/purchases/authorize-200.xml
@@ -58,6 +58,12 @@ Location: https://api.recurly.com/v2/invoices
         <created_at nil="nil"></created_at>
         <updated_at nil="nil"></updated_at>
         <revenue_schedule_type>at_invoice</revenue_schedule_type>
+        <custom_fields type="array">
+          <custom_field>
+            <name>size</name>
+            <value>small</value>
+          </custom_field>
+        </custom_fields>
       </adjustment>
     </line_items>
     <transactions type="array">
diff --git a/Tests/fixtures/purchases/cancel-200.xml b/Tests/fixtures/purchases/cancel-200.xml
index d0159979..f8bbce00 100644
--- a/Tests/fixtures/purchases/cancel-200.xml
+++ b/Tests/fixtures/purchases/cancel-200.xml
@@ -58,6 +58,12 @@ Location: https://api.recurly.com/v2/invoices
         <created_at nil="nil"></created_at>
         <updated_at nil="nil"></updated_at>
         <revenue_schedule_type>at_invoice</revenue_schedule_type>
+        <custom_fields type="array">
+          <custom_field>
+            <name>size</name>
+            <value>small</value>
+          </custom_field>
+        </custom_fields>
       </adjustment>
     </line_items>
     <transactions type="array">
diff --git a/Tests/fixtures/purchases/capture-200.xml b/Tests/fixtures/purchases/capture-200.xml
index e59dfdeb..285fc16e 100644
--- a/Tests/fixtures/purchases/capture-200.xml
+++ b/Tests/fixtures/purchases/capture-200.xml
@@ -58,6 +58,12 @@ Location: https://api.recurly.com/v2/invoices
         <created_at nil="nil"></created_at>
         <updated_at nil="nil"></updated_at>
         <revenue_schedule_type>at_invoice</revenue_schedule_type>
+        <custom_fields type="array">
+          <custom_field>
+            <name>size</name>
+            <value>small</value>
+          </custom_field>
+        </custom_fields>
       </adjustment>
     </line_items>
     <transactions type="array">
diff --git a/Tests/fixtures/purchases/create-201.xml b/Tests/fixtures/purchases/create-201.xml
index ab7db846..2de95487 100644
--- a/Tests/fixtures/purchases/create-201.xml
+++ b/Tests/fixtures/purchases/create-201.xml
@@ -70,6 +70,12 @@ Location: https://api.recurly.com/v2/invoices/3704
           <country>US</country>
           <nickname>Home</nickname>
         </shipping_address>
+        <custom_fields type="array">
+          <custom_field>
+            <name>size</name>
+            <value>small</value>
+          </custom_field>
+        </custom_fields>
       </adjustment>
     </line_items>
     <transactions type="array">
diff --git a/Tests/fixtures/purchases/pending-200.xml b/Tests/fixtures/purchases/pending-200.xml
index cd9e9114..70dc5ef3 100644
--- a/Tests/fixtures/purchases/pending-200.xml
+++ b/Tests/fixtures/purchases/pending-200.xml
@@ -58,6 +58,12 @@ Location: https://api.recurly.com/v2/invoices
         <created_at nil="nil"></created_at>
         <updated_at nil="nil"></updated_at>
         <revenue_schedule_type>at_invoice</revenue_schedule_type>
+        <custom_fields type="array">
+          <custom_field>
+            <name>size</name>
+            <value>small</value>
+          </custom_field>
+        </custom_fields>
       </adjustment>
     </line_items>
     <transactions type="array">
diff --git a/Tests/fixtures/purchases/preview-200.xml b/Tests/fixtures/purchases/preview-200.xml
index cd9e9114..70dc5ef3 100644
--- a/Tests/fixtures/purchases/preview-200.xml
+++ b/Tests/fixtures/purchases/preview-200.xml
@@ -58,6 +58,12 @@ Location: https://api.recurly.com/v2/invoices
         <created_at nil="nil"></created_at>
         <updated_at nil="nil"></updated_at>
         <revenue_schedule_type>at_invoice</revenue_schedule_type>
+        <custom_fields type="array">
+          <custom_field>
+            <name>size</name>
+            <value>small</value>
+          </custom_field>
+        </custom_fields>
       </adjustment>
     </line_items>
     <transactions type="array">
diff --git a/lib/recurly/adjustment.php b/lib/recurly/adjustment.php
index 796ed14d..1d9ded80 100644
--- a/lib/recurly/adjustment.php
+++ b/lib/recurly/adjustment.php
@@ -38,9 +38,15 @@
  * @property DateTime $start_date A timestamp associated with when the adjustment began.
  * @property DateTime $end_date A timestamp associated with when the adjustment ended.
  * @property DateTime $created_at A timestamp associated with when the adjustment was created.
+ * @property Recurly_CustomFieldList $custom_fields Optional custom fields for the adjustment.
  */
 class Recurly_Adjustment extends Recurly_Resource
 {
+  public function __construct($href = null, $client = null) {
+    parent::__construct($href, $client);
+    $this->custom_fields = new Recurly_CustomFieldList();
+  }
+
   public static function get($adjustment_uuid, $client = null) {
     return Recurly_Base::_get(self::_safeUri(Recurly_Client::PATH_ADJUSTMENTS, $adjustment_uuid), $client);
   }
@@ -122,7 +128,7 @@ protected function getWriteableAttributes() {
       'currency', 'unit_amount_in_cents', 'quantity', 'quantity_decimal', 'description',
       'accounting_code', 'tax_exempt', 'tax_inclusive', 'tax_code', 'start_date', 'end_date',
       'revenue_schedule_type', 'origin', 'product_code', 'credit_reason_code',
-      'shipping_address', 'shipping_address_id', 'item_code', 'external_sku'
+      'shipping_address', 'shipping_address_id', 'item_code', 'external_sku', 'custom_fields'
     );
   }
 }