Finkelstein was trained as a field archaeologist in the excavations of Tel Beer Sheva (1971, Director: Yohanan Aharoni) and Tel Aphek (1973–1978, Directors: Moshe Kochavi and Pirhiya Beck). The site features Middle Bronze, Late Bronze and Iron I remains. Finkelstein (ed.), Shiloh: The Archaeology of a Biblical Site (Monograph Series of the Institute of Archaeology Tel Aviv University 10), Tel Aviv 1993. According to Finkelstein's Low Chronology, the Iron Age I lasted until the middle of the 10th century BCE, while the Iron IIA is dated between the middle of the 10th century and ca. This means that the Megiddo palaces and other features which had traditionally been attributed to the time of King Solomon – features which date to the late Iron IIA – should indeed be associated with the endeavors of the Omride Dynasty in the first half of the 9th century BCE. Starting in the late 1990s, the focus of the discussion shifted to the interpretation of radiocarbon determinations for organic samples from key sites, such as Tel Rehov and Megiddo.
His great grandfather on his mother's side, Shlomo Ellenhorn, came to Palestine from Grodno (today in Belarus) in the 1850s and settled in Hebron.In 1987 he was appointed an associate professor with tenure at Bar-Ilan University and in 1990 moved to the Department of Archaeology and Ancient Near Eastern Civilizations at Tel Aviv University. Halpern (eds.), Megiddo IV: The 1998–2002 Seasons (Monograph Series of the Institute of Archaeology Tel Aviv University 24), Tel Aviv 2006. Finkelstein explained these oscillations as representing changes along the sedentary/ pastoral-nomadic continuum, which were caused by socioeconomic and political dynamics.In 1992/93 Finkelstein spent a sabbatical year as a visiting scholar at the Department of Near Eastern Languages and Civilizations, Harvard University. Hence, a big portion of the people who settled in the highlands in the early Iron Age were locals of a pastoral-nomadic background.He was one of the first physicians in the Bikur Cholim Hospital in Jerusalem, and is listed among the group of people who purchased the land in 1878 in order to establish Petah Tikva – the first modern Jewish settlement in Palestine outside the four holy cities.Finkelstein's grandfather, Israel Jacob Ellenhorn, was the first pharmacist in Petah Tikva.