Joseph ibn Migash was probably born in Seville (though Steinschneider believes it was Granada). He moved to Lucena at the age of 12 to study under the renowned Talmudist Isaac Alfasi. He studied under Alfasi at Lucena for fourteen years. Shortly before his death (1103), Alfasi ordained Ibn Megas as a rabbi, and - passing over his own son - also appointed him, then 26, to be his successor as Rosh Yeshiva (seminary head). Joseph ibn Migash held this position for 38 years.