The transition to kindergarten is a critical period for children and families, with successful transitions setting the stage for short- and long-term academic and social success. This study explored the practices used by kindergarten teachers to help ease children's and families' transition into primary school (termed "transition practices"), and assessed their relationship to children's social and academic adjustment to school in a nationally representative sample of children in the United States (N = 4,900). On average, kindergarten teachers engaged in 3 transition practices, with outreach to parents and child or parent classroom visits most common, and structural changes to the school schedule less frequent. Private schools and more experienced teachers engaged in more transition practices, whereas ethnic and racial minority, immigrant, and urban children had teachers who reported fewer practices. Prospective, lagged regression models found that engagement in more types of transition practices was predictive of heightened prosocial behaviors among children, but was not associated with children's attention or academic outcomes. Examination of specific types of practices found that transition activities geared toward parents were associated with children's heightened academic skills in kindergarten. These results provide limited evidence to support the "more is better" view of transition practices and instead suggest that specific types of transition practices are linked to particular aspects of children's functioning.