This paper documents what is known about homeless encampments as of late 2018, based on a review of the limited literature produced by academic and research institutions and public agencies, supplemented by interviews with key informants. This paper is part of a larger research study, sponsored jointly by the U.S. Department of Housing and Urban Development’s Office of Policy Development and Research and the U.S. Department of Health and Human Services’s Office of the Assistant Secretary for Planning and Evaluation. The goal is to contribute to the understanding of homelessness, including the characteristics of homeless encampments and the people who stay in them, and of local responses addressing encampments and their associated costs. The larger final research report is anticipated January 2020.