Russell Fuller discusses the practice of polygamy in ancient Israel.
Russell Fuller, "Marriage," in The Oxford Guide to Ideas & Issues of the Bible, ed. Bruce M. Metzger and Michael D. Coogan (New York: Oxford University Press, 2001), 339
Although monogamy may have been the ideal, polygamy was accepted and practiced throughout Israel's history, although to what extent we cannot be sure, since the sources for the most part are derived from and describe the elite ruling and upper classes. The patriarchs took more than one wife, and the kings of Israel and Judah maintained harems, of which Solomon's was the most notorious. By the Roman period, monogamy seems to have been the common practice.