Using data from a survey on cognitive proficiency levels of first graders in Switzerland (N = 1.830), this study analyzes (1) who has access to institutional childcare, (2) whether institutional childcare affects cognitive skills of children who differ in terms of socioeconomic status, home literacy, native country, and home language, and (3) how duration and intensity of childcare affect children's skills. The findings indicate sociocultural disparities in access to childcare. Multiple hierarchical regression analyses suggest that childcare experience did not enhance children's outcomes when social and cultural background characteristics were held constant. For childcare attendees, however, a longer duration of attendance had a positive effect on vocabulary and a higher intensity was related negatively to vocabulary. Children who did not speak German at home benefitted more from childcare in terms of vocabulary skills than German-speaking children. Social background was a significant predictor of vocabulary and math skills. Cultural background additionally impacted on vocabulary skills when social background was controlled for. Implications for policy are discussed.