National numismatic organization devoted to error and variety collectors.

Just as nearly every family has its black sheep, virtually every coin series has its failures. These are known as errors or mis-struck coins, and have a following all their own.

Available both as a print magazine and an online PDF magazine with articles, features, and discoveries of major mint errors (striking errors) from the United States and around the world.

Monthly magazine devoted to error coin collecting. Available by subscription.

Information regarding errors on the 2007 George Washington dollar coin.

Photographic image library of coins with doubled dies, repunched mintmarks, over mintmarks, and repunched dates.

Census for US coins with major die rotation of 90 degrees to 180 degrees. Includes fake error detection and measurement indices.

Describes and illustrates dramatically mis-struck foreign coins. Includes information on recognizing various types of error coins as well as articles on how to get started collecting them.