BACKGROUND: Internal migration, mostly composed of young adults and the poor, constitutes the largest flow of people in developing countries. Few studies document the patterns and determinants of internal youth migration in sub-Saharan Africa. OBJECTIVES: This paper analyzes the socioeconomic determinants of the decisions among young adults to internally migrate in Senegal. We focus on whether their decisions to migrate are influenced by individual characteristics, as well as the circumstances in the households and communities where young adults grew up, and whether these factors are differentiated by gender. METHODS: Using a unique migration household survey in Senegal, we estimate multinomial logit models to analyze the role of childhood socioeconomic determinants in later youth migration decisions to rural and urban areas. RESULTS: We find that young people undertake mostly rural-to-rural and urban-to-urban migrations, and over half of them are temporary migrants. We also find that the determinants are heterogeneous by gender and destination. The higher the fathers' education, the more (less) likely are their daughters to move to urban (rural) areas. Young individuals who spend their childhood in betteroff households are more likely to move to urban areas. The presence of younger siblings during childhood increases the propensity of moving to rural areas. Access to primary schools from the childhood residence decreases the likelihood of migrating to urban areas for both men and women. CONTRIBUTION: We contribute to the sparse literature on internal youth migration in developing countries by highlighting the relevance of the family- and community-level characteristics during childhood in predicting later migration in life.