The early twenty-first century has seen increased attention to developing young children's social-emotional skills and competencies in preschool programs, including Head Start--the largest federally funded early-childhood education program in the United States. At the same time, there has been greater recognition of the importance of adapting evidence-based programs to meet the needs of special populations such as the children and families of migrant and seasonal workers. The Head Start Classroom-based Approaches and Resources for Emotion and Social skill promotion (CARES) demonstration, which evaluated three strategies that were designed to improve the social-emotional development of children in Head Start classrooms, provided an opportunity to study the adaptation and implementation of an existing evidence-based, social-emotional curriculum for such a population. The curriculum, called Preschool PATHS (Promoting Alternative Thinking Strategies), was offered through the Migrant and Seasonal Head Start (MSHS) program, which is operated across the country and is the subject of this report. The Head Start CARES demonstration was supported by the Office of Planning, Research and Evaluation in the Administration for Children and Families (ACF), U.S. Department of Health and Human Services (HHS), and was conducted by MDRC, a nonprofit, nonpartisan education and social policy research organization, in collaboration with MEF Associates and several academic partners. This case study describes methods for delivering social-emotional programs in MSHS settings, as well as features inherent in MSHS centers and the characteristics of the children in MSHS programs, that can inform adaptations of other program models to these settings. In addition, the lessons from this study are relevant to the considerable debate about how best to balance the competing demands of fidelity to the core components of an evidence-based model with the need to adapt the model for special populations or special circumstances. Four classrooms from two MSHS grantees were involved in this case study. Both grantees enthusiastically participated in the project. The researchers collected information on program implementation from a variety of sources, including site visits and logs kept by teacher coaches and trainers (who were part of the program's professional development component, described later), as well as interviews with program staff and parents. While the study does not test the impact of Preschool PATHS in the MSHS context--that is, the effect it has on children's social-emotional outcomes--it provides a rich set of qualitative and quantitative information about the two grantees' implementation experience. And, even though the sample is small and not representative of the broader MSHS grantee community, examining the experience of these two grantees is a first step in understanding how well such programs can be adapted to this context. The MSHS CARES experience suggests that adaptations can account for important cultural differences while staying true to the core principles and components of evidence-based programs. The following are appended: (1) Coach and Trainer Management Information System (MIS) Logs; (2) Implementation Site Visit Interview Protocols and Parent Discussion Group Guide; (3) Coach and Teacher Training Forms and Parent Session Feedback Forms; and (4) Registrants for the Migrant and Seasonal Head Start CARES Meeting, November 8, 2010.