Studies Jewish-Arab relations in Eretz Israel/Palestine from the late Ottoman period up to the present. He has published in Hebrew, English and Arabic on Palestinian collaborators, Israeli security agencies, Jews and Arabs in Mandatory Palestine, Palestinians in Jerusalem, the Palestinian refugee problem and more.

He is the head of the Cherrick Center for the Study of Zionism at the Hebrew University and was appointed visiting professor at New York University (2014) and at Dartmouth College (2016). Among his books: Year Zero of the Arab-Israeli Conflict 1929 (Brandeis University Press, 2016); Good Arabs: The Israeli Security Agencies and the Israeli Arabs (University of California Press, 2011).