This research compared the relative impact of different preschool activities on the development of bilingual students' English-language skills. The study investigated whether bilingual preschool children would engage more, and use more of their second language (English), during free-play (non-academic) versus teacher-structured (academic) activities. The researcher utilized both quantitative and qualitative research approaches; data sources included 285 preschool observations made in three classrooms in Northern California. Data analysis consisted of descriptive statistics (e.g. frequencies/percentages, mean values, and standard deviations). In addition, children's observed scores were also analyzed by normative scales using standardized z-scores. The findings of this study indicated that bilingual children engaged and interacted significantly more during free-play (non-academic) preschool classroom activities than during teacher-structured (academic) activities. Specific free-play activities enabling optimal engagement and second language acquisition were pretend play, free play, and monkey bars. The study's major implication is that free-play (non-academic) activities may be much more helpful in developing bilingual preschoolers' English-language skills than teacher-structured (academic) activities. Free-play activities are an affordance for making language available, which helps with building academic skills and cultural capital. This study proves that free-play activities are an affordance for language learning because bilingual children have shown dramatically greater engagement in non-academic activities (vs academic activities). The importance of free-play activities may extend beyond preschool classrooms (e.g. greater English-language development in early preschool may subsequently positively impact student performance in kindergarten). Thus, unstructured, social-based activities should be implemented for bilingual students in K-12 classrooms. Free-play (i.e. non-academic) activities should be implemented in preschool.