Rabbi Yosef Caro was a prolific writer, authoring works in several major areas of Jewish literary endeavor -- parshanut (commentary on Scripture), Talmudic methodology, ethical works, Kabbala, responsa, and of course his major works in halacha.
Beit Yosef: Written as a comprehensive commentary on the Tur (a compendium of halachic-legal rulings written by Rabbeinu Yaakov ben Asher 5035-5109 (1275-1349 CE)), it took him 20 years to write. In the Beit Yosef, Rabbi Yosef gathered the opinions and decisions of all the major authorities up until his time, on every halachic matter, and cross-referenced them. He ruled between differing views on the basis of a consensus between the three preeminent halachic authorities, Rabbi Yitzchak Alfasi (the Rif), Rabbi Moshe ben Maimon (the Rambam / Maimonides) and Rabbeinu Asher (the Rosh). Where there was a disagreement between these three giants, he ruled according to the majority view. In the event that these authorities did not rule at all in the matter, he followed the majority opinion between Rabbi Moshe ben Nachman (the Ramban / Nachmanides), Rabbi Shlomo ben Aderet (the Rashba) and Rabbeinu Nissim (the Ran). Since he was of Sefardic (Spanish) origin, his rulings largely follow the opinions of the Sefardic sages, with very little reference to the sages of Tzarfat (France) and Ashkenaz (Germany and its environs). Although the work was completed and published in 5302 (1542 CE), he continued to edit and refine it for the next 12 years, eventually publishing it in a second edition together with the Tur, in several volumes: Orach Chaim in Venice 5310-11 (1550-51 CE); Yoreh De'ah in Venice 5311 (1551 CE); Even HaEzer in Savionita 5313 (1553 CE) and Choshen Mishpat in Savionita 5319 (1559 CE).
Rabbi Chaim Yosef David Azulai (the Chida) writes that the work was not without its opponents. One of the leading halachic authorities of the time, Rabbi Yosef ibn Lev, instructed his students not to use it since they would come to rely on it, with a resultant loss in their own expertise in the original sources. When he taught his students from the Tur, he had always cited from memory all the sources on which the Tur had based his rulings, never forgetting a source. After the Beit Yosef was published, it happened once that he could not remember the source for a certain ruling. After searching for it in vain, he declared, "I see that Heaven wants the Beit Yosef to be widely used. Go and look up the reference there!" Indeed, the students found the proper reference there -- the source was in a given tractate of the Talmud. From then on Rabbi Yosef ibn Lev allowed his students to learn from the Beit Yosef.
Initially, his work was greeted with great opposition from several sages to the east and the west.
Shulchan Aruch: After he had completed the Beit Yosef, Rabbi Caro made a summary of his rulings in the Beit Yosef, in the form of an index, without reference to sources, and titled it Shulchan Aruch ("Laid Table"). It was completed in 5315 (1555 CE) in Israel in a town near Safed but was first published in Venice in 5325 (1565 CE). Although Rabbi Caro himself did not initially place great importance on this work, intending it merely as a reference guide, it soon came to be regarded as the most authoritative and reliable compendium of halachic rulings.
Initially, this work also was greeted with great opposition from several sages to the east and the west. They argued that the work had not been written as a codex of halacha and vehemently opposed its use in halachic decisions without a prior review and analysis of the appropriate sources in the Talmud and other codifiers. In addition, Ashkenazic sages pointed out that the work was based almost exclusively on Sefardic authorities and was therefore liable to displace the writings of French and German authorities. One of these opponents was Rabbi Moshe Isserlis (the Rama), who noted all the places where the Shulchan Aruch ruled against the decisions and customs of the sages of Germany and its environs. By Divine Providence this controversy was actually beneficial in spreading the fame and usage of the work until it became the halachic norm wherever the Rama did not disagree. Eventually, the Rama's gloss (called HaMapa -- "The Tablecloth") was published together with the Shulchan Aruch in Cracow in 5338 (1578 CE), and together they became the universally recognized Code of Jewish Law.
Kesef Mishneh: A commentary on Maimonides' Mishneh Torah. The Rambam had published his magnum opus without references for his rulings. The Maggid Mishna, an important commentary on Mishneh Torah written by Rabbi Vidal di Tolouse, had referenced six of the fourteen sections of the work, and Rabbi Caro set out to complete the references, while at the same time explaining the Rambam's view and defending it from the Raavad, who had refuted many rulings of the Rambam. The Kesef Mishneh, as it was called, was published in Venice between the years 5334-5336 (1574-76 CE) and was subsequently published with almost every edition of Mishneh Torah.
Bedek HaBayit: Additional notes on his Beit Yosef in response to critics (Salonica, 5365).
Responsa: Rabbi Caro corresponded with many of the leading rabbis of the generation regarding important halachic matters. His correspondence was gathered together and published posthumously. One volume, his responsa on Even HaEzer, was published by his son Yehuda in Salonica in 5358. Other responsa were published much later under the title Avkat Rachel (Izmir, 5555).
Klalei HaGemara: A volume on Talmudic methodology, published together with Rabbi Yehoshua HaLevi's Halichot Olam in Salonica in 5358.
Or Tzadikim: Commentary on the Torah, Shir HaShirim (Song of Songs), and Pirkei Avot (Ethics of Our Fathers), published together with commentaries by other authors (Salonica, 5359). He also wrote a commentary on Mishlei (Proverbs) that was never published.
A Super-commentary on Rashi's and Ramban's commentaries on the Torah was never published. It is mentioned in the introduction to the volume of responsa published by his son.
Maggid Meisharim: Rabbi Caro's only overtly kabbalistic work, comprising teachings that he learned from a heavenly maggid, an angel that privately taught him. It was published in two parts: the first part, covering Bereishit to Metzora, was published in Lublin in 5405; the second part, completing the Torah and on Prophets and Writings, was published in Venice in 5414. Rabbi Chaim David Azulai (the Chida) notes that only about one fiftieth of the manuscript was ever published.
The work covers an astonishing variety of subjects, including ethical exhortations, explanations of the ten sefirot, secrets of Creation, the Divine Names, levels of the soul, treatises on the revelation of Elijah the Prophet, reincarnation and resurrection of the dead, miracles, Divine Providence and free choice, dream interpretation, the mystical intentions of eating, the mystical intentions of some of the mitzvot, the nature of sin and the harm it causes, and mystical interpretations of passages in the Torah. For sample selections, click here.