The invention provides Cripto-specific antibodies, or biologically functional fragments thereof, and uses thereof. Antibodies which bind Cripto and inhibit Cripto activity are provided. Antibodies which bind Cripto and inhibit the interaction between Cripto and ALK4 and/or between Cripto and Activin B are provided. Antibodies which bind Cripto and inhibit tumor growth are also provided. Antibodies which bind Cripto, inhibit Cripto activity, and inhibit tumor growth are also provided. The invention also provides methods of using these antibodies in therapeutic, diagnostic, and research applications.