The story of the composition and reception of the sixteenth-century code of Jewish law, the Shulḥan ‘Arukh, has been told by many scholars, including my late teacher, Professor Isadore Twersky.Isadore Twersky, “The Shulḥan ‘Arukh: Enduring Code of Jewish Law,” Judaism 16 (1967), 141–158, reprinted in The Jewish Expression, ed. Judah Goldin (New Haven, 1976), pp. 322–343. Cf. Isadore Twersky, “Ha-Rav Yosef Qaro ba‘al ha-Shulḥan ‘Arukh,” Asufot 3 (1989), 245–262. See also Chaim Tchernowitz, Toledot ha-Posqim, vol. 3 (New York, 1947); Yizhaq Raphael, ed., Rabi Yosef Qaro: ‘Iyunim u-meḥqarim be-mishnat Maran Ba‘al ha-Shulḥan ‘Arukh (Jerusalem, 1969); Menachem Elon, Ha-Mishpat ha-‘Ivri: toledotav, meqorotav, ‘eqronotav, 2nd ed. (Jerusalem, 1978); Asher Siev (Ziv), Rabeinu Mosheh Isserles (Rema) (New York, 1972); R. J. Zwi Werblowsky, Joseph Karo: Lawyer and Mystic, rev. ed. (Philadelphia, 1977); Meir Benayahu, Yosef Beḥiri: Maran Rabi Yosef Qaro (Jerusalem, 1991); Israel Ta-Shma, “Rabbi Joseph Caro and His Beit Yosef: Between Spain and Germany,” in Moreshet Sepharad: The Sephardi Legacy, ed. Haim Beinart, vol. 2 (Jerusalem, 1992), pp. 192–206 (the article originally appeared in Hebrew in Tarbiz 59 : 153–170); Eric (Yizhaq) Zimmer, Gaḥalatan shel Ḥakhamim: peraqim be-toledot ha-rabanut be-Germanyah ba-me'ah ha-shesh-‘esreh uva-me'ah ha-sheva‘-‘esreh (Jerusalem, 1999), pp. 177–237. It is intertwined with a second story, namely, the formation of Ashkenazic Jewish identity.An excellent recent study of identity-formation among a group of early modern Jews is Miriam Bodian, Hebrews of the Portuguese Nation: Conversos and Community in Early Modern Amsterdam (Bloomington, IN, 1997). The formation of Polish Jewish identity was the topic of Adam Teller's lecture, “Yeven Metzula and the Formation of Jewish Self-Consciousness in Eastern Europe,” which I was privileged to hear, and which is expected to appear in Jewish History in a special issue on the massacres of 1648. On the treatment of Ashkenazic and Sefardic Jews in Jewish historiography, see Ismar Schorsch, “The Myth of Sephardic Supremacy,” Leo Baeck Institute Year Book 34 (1989), 47–66. On halakhic aspects of the differences between the two groups, see Hirsch Jacob Zimmels, Ashkenazim and Sephardim: Their Relations, Differences, and Problems as Reflected in the Rabbinical Responsa (Oxford, 1958).