We examined the association between Spanish-speaking preschoolers’ (N = 137; M age = 53 months; SD = 4 months; 53% boys) effortful control (EC) and English vocabulary and letter-word skills. We also examined whether close teacher-child relationships and classroom engagement mediated the association between EC and English vocabulary and letter-word skills and whether that mediated association varied based on parents’ and preschoolers’ English use at home. Data were gathered using teacher and parent surveys and child standardized assessments. The results revealed a positive association between preschoolers’ EC in the fall of preschool and their English vocabulary and letter-word skills in the following spring. The association was mediated through close teacher-child relationships and classroom engagement, but only at certain levels of parents’ and preschoolers’ English use at home. The findings highlight the important role that EC may play in fostering Spanish-speaking preschoolers’ English skills and the classroom socioemotional processes by which that association operates as a function of their linguistic experiences in English at home. (author abstract)