Although Miles has basically hit the nail on the head, there are other acceptable authorised release certificates other than the EASA Form 1 and that depends on their originating from an organisation whose state has a bilateral in force. Some JAA Forms 1 are still acceptable.
Parts originating from the USA for fitment to EASA comercial aircraft must come from EASA-approved FAR 145 organiations. FAA 8130-3 with EASA release statement (dual release) required for large and commercial aircraft parts (maintained under Part 145); the FAA 8130-3 does not have to be dual release for aircraft maintained under Part M Subpart F (non-commercial/non-large) but the organisation must have a method of assessing such parts. Canadian and Brazilian forms are also acceptable but you need to read Part 145, MIP-G, AAM and other stuff.
There are changes afoot for the Form 1 (Opinion 06/2008) and FAA 8130-3 (going to be called FAA Form 1, I think).
Drop me a PM for further info.