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