This literature review aims to understand who is and is not being served by Head Start among families experiencing adversity; the range of recruitment, selection, enrollment, and retention (RSER) strategies that programs use with families experiencing adversity; the factors that shape the use of RSER strategies; and the effectiveness of specific strategies with these populations. The review also reveals gaps in knowledge and opportunities for future research related to the RSER strategies that support families experiencing adversity. It explores how commonly families eligible for Head Start experience specific adversities, how more than one of those adversities can be faced simultaneously by the same family (that is, co-occur), and the factors that help determine how families experience those adversities. The primary research questions include: (1) How commonly are Head Start-eligible families experiencing specific adversities? Do these adversities co-occur and, if so, in what way and in what likely combinations?; (2) Which factors shape or influence the RSER strategies that Head Start programs use? What factors shape the effectiveness of RSER strategies used by programs?; and (3) Which RSER approaches are the most promising for recruiting, selecting, enrolling, and retaining families experiencing adversity and facing barriers in Head Start programs? [This report was co-produced by Brazelton Touchpoints Center.]