diff --git a/lib/Event.php b/lib/Event.php
index c30d3e3d9..2add5ce11 100644
--- a/lib/Event.php
+++ b/lib/Event.php
@@ -19,6 +19,96 @@
  */
 class Event extends ApiResource
 {
+     /**
+     * Possible string representations of event types.
+     * @link https://stripe.com/docs/api#event_types
+     */
+    const ACCOUNT_UPDATED                      = 'account.updated';
+    const ACCOUNT_APPLICATION_DEAUTHORIZED     = 'account.application.deauthorized';
+    const ACCOUNT_EXTERNAL_ACCOUNT_CREATED     = 'account.external_account.created';
+    const ACCOUNT_EXTERNAL_ACCOUNT_DELETED     = 'account.external_account.deleted';
+    const ACCOUNT_EXTERNAL_ACCOUNT_UPDATED     = 'account.external_account.updated';
+    const APPLICATION_FEE_CREATED              = 'application_fee.created';
+    const APPLICATION_FEE_REFUNDED             = 'application_fee.refunded';
+    const APPLICATION_FEE_REFUND_UPDATED       = 'application_fee.refund.updated';
+    const BALANCE_AVAILABLE                    = 'balance.available';
+    const CHARGE_CAPTURED                      = 'charge.captured';
+    const CHARGE_FAILED                        = 'charge.failed';
+    const CHARGE_PENDING                       = 'charge.pending';
+    const CHARGE_REFUNDED                      = 'charge.refunded';
+    const CHARGE_SUCCEEDED                     = 'charge.succeeded';
+    const CHARGE_UPDATED                       = 'charge.updated';
+    const CHARGE_DISPUTE_CLOSED                = 'charge.dispute.closed';
+    const CHARGE_DISPUTE_CREATED               = 'charge.dispute.created';
+    const CHARGE_DISPUTE_FUNDS_REINSTATED      = 'charge.dispute.funds_reinstated';
+    const CHARGE_DISPUTE_FUNDS_WITHDRAWN       = 'charge.dispute.funds_withdrawn';
+    const CHARGE_DISPUTE_UPDATED               = 'charge.dispute.updated';
+    const CHARGE_REFUND_UPDATED                = 'charge.refund.updated';
+    const COUPON_CREATED                       = 'coupon.created';
+    const COUPON_DELETED                       = 'coupon.deleted';
+    const COUPON_UPDATED                       = 'coupon.updated';
+    const CUSTOMER_CREATED                     = 'customer.created';
+    const CUSTOMER_DELETED                     = 'customer.deleted';
+    const CUSTOMER_UPDATED                     = 'customer.updated';
+    const CUSTOMER_DISCOUNT_CREATED            = 'customer.discount.created';
+    const CUSTOMER_DISCOUNT_DELETED            = 'customer.discount.deleted';
+    const CUSTOMER_DISCOUNT_UPDATED            = 'customer.discount.updated';
+    const CUSTOMER_SOURCE_CREATED              = 'customer.source.created';
+    const CUSTOMER_SOURCE_DELETED              = 'customer.source.deleted';
+    const CUSTOMER_SOURCE_EXPIRING             = 'customer.source.expiring';
+    const CUSTOMER_SOURCE_UPDATED              = 'customer.source.updated';
+    const CUSTOMER_SUBSCRIPTION_CREATED        = 'customer.subscription.created';
+    const CUSTOMER_SUBSCRIPTION_DELETED        = 'customer.subscription.deleted';
+    const CUSTOMER_SUBSCRIPTION_TRIAL_WILL_END = 'customer.subscription.trial_will_end';
+    const CUSTOMER_SUBSCRIPTION_UPDATED        = 'customer.subscription.updated';
+    const FILE_CREATED                         = 'file.created';
+    const INVOICE_CREATED                      = 'invoice.created';
+    const INVOICE_PAYMENT_FAILED               = 'invoice.payment_failed';
+    const INVOICE_PAYMENT_SUCCEEDED            = 'invoice.payment_succeeded';
+    const INVOICE_SENT                         = 'invoice.sent';
+    const INVOICE_UPCOMING                     = 'invoice.upcoming';
+    const INVOICE_UPDATED                      = 'invoice.updated';
+    const INVOICEITEM_CREATED                  = 'invoiceitem.created';
+    const INVOICEITEM_DELETED                  = 'invoiceitem.deleted';
+    const INVOICEITEM_UPDATED                  = 'invoiceitem.updated';
+    const ORDER_CREATED                        = 'order.created';
+    const ORDER_PAYMENT_FAILED                 = 'order.payment_failed';
+    const ORDER_PAYMENT_SUCCEEDED              = 'order.payment_succeeded';
+    const ORDER_UPDATED                        = 'order.updated';
+    const ORDER_RETURN_CREATED                 = 'order_return.created';
+    const PAYOUT_CANCELED                      = 'payout.canceled';
+    const PAYOUT_CREATED                       = 'payout.created';
+    const PAYOUT_FAILED                        = 'payout.failed';
+    const PAYOUT_PAID                          = 'payout.paid';
+    const PAYOUT_UPDATED                       = 'payout.updated';
+    const PING                                 = 'ping';
+    const PLAN_CREATED                         = 'plan.created';
+    const PLAN_DELETED                         = 'plan.deleted';
+    const PLAN_UPDATED                         = 'plan.updated';
+    const PRODUCT_CREATED                      = 'product.created';
+    const PRODUCT_DELETED                      = 'product.deleted';
+    const PRODUCT_UPDATED                      = 'product.updated';
+    const RECIPIENT_CREATED                    = 'recipient.created';
+    const RECIPIENT_DELETED                    = 'recipient.deleted';
+    const RECIPIENT_UPDATED                    = 'recipient.updated';
+    const REVIEW_CLOSED                        = 'review.closed';
+    const REVIEW_OPENED                        = 'review.opened';
+    const SIGMA_SCHEDULED_QUERY_RUN_CREATED    = 'sigma.scheduled_query_run.created';
+    const SKU_CREATED                          = 'sku.created';
+    const SKU_DELETED                          = 'sku.deleted';
+    const SKU_UPDATED                          = 'sku.updated';
+    const SOURCE_CANCELED                      = 'source.canceled';
+    const SOURCE_CHARGEABLE                    = 'source.chargeable';
+    const SOURCE_FAILED                        = 'source.failed';
+    const SOURCE_MANDATE_NOTIFICATION          = 'source.mandate_notification';
+    const SOURCE_TRANSACTION_CREATED           = 'source.transaction.created';
+    const TOPUP_CREATED                        = 'topup.created';
+    const TOPUP_FAILED                         = 'topup.failed';
+    const TOPUP_SUCCEEDED                      = 'topup.succeeded';
+    const TRANSFER_CREATED                     = 'transfer.created';
+    const TRANSFER_REVERSED                    = 'transfer.reversed';
+    const TRANSFER_UPDATED                     = 'transfer.updated';
+
     use ApiOperations\All;
     use ApiOperations\Retrieve;
 }