diff --git a/falcon/status_codes.py b/falcon/status_codes.py
index 568cd81..6b9dda2 100644
--- a/falcon/status_codes.py
+++ b/falcon/status_codes.py
@@ -90,6 +90,12 @@ HTTP_418 = "418 I'm a teapot"
 HTTP_IM_A_TEAPOT = HTTP_418
 HTTP_426 = '426 Upgrade Required'
 HTTP_UPGRADE_REQUIRED = HTTP_426
+HTTP_428 = '428 Precondition Required'
+HTTP_PRECONDITION_REQUIRED = HTTP_428
+HTTP_429 = '429 Too Many Requests'
+HTTP_TOO_MANY_REQUESTS = HTTP_429
+HTTP_431 = '431 Request Header Fields Too Large'
+HTTP_REQUEST_HEADER_FIELDS_TOO_LARGE = HTTP_431
 
 HTTP_500 = '500 Internal Server Error'
 HTTP_INTERNAL_SERVER_ERROR = HTTP_500
@@ -103,6 +109,8 @@ HTTP_504 = '504 Gateway Time-out'
 HTTP_GATEWAY_TIMEOUT = HTTP_504
 HTTP_505 = '505 HTTP Version not supported'
 HTTP_HTTP_VERSION_NOT_SUPPORTED = HTTP_505
+HTTP_511 = '511 Network Authentication Required'
+HTTP_NETWORK_AUTHENTICATION_REQUIRED = HTTP_511
 
 # 70X - Inexcusable
 HTTP_701 = '701 Meh'