This work is concerned with the origin, nature and circulation of the manuscripts of the ספר מצות קטן (Sefer Mitzvot Katan, or SeMaK for short) in ­14th-century Ashkenaz.1 The Sefer Mitzvot Katan is a halakhic work written by Rabbi Isaac ben Joseph of Corbeil in the second half of the 13th century. A concise volume of commandments, it came to enjoy considerable popularity among the Jewish communities of Zarfat and Ashkenaz. At least 229 whole or fragmented SeMaK manuscripts have survived to this day,2 most of which were produced in the Ashkenazi region in the 14th and 15th century.