Adopting an "act-in-context" approach is helpful to researchers investigating situational variability in children's active engagement in preschool classrooms. Aligned with this approach, we propose an empirical pathway and a conceptual model to support examinations of contextual factors hypothesized to impact active engagement as well as the means by which adults promote it. We defined two overarching factors--cognitive and organizational--and explored the predictive nature of seven features within them. With video recordings from 31 classrooms (inclusive and self-contained) of three instructional routines on three different occasions, we derived averages for classwide active engagement during each observation. A series of linear mixed effects models revealed that instructional routines significantly predicted variability in classwide active engagement as did interactions of other contextual features with instructional routines. These findings provide a foundation for continued, systematic examinations of situational factors and conceptualizations of engagement within carefully specified pathways for improving active engagement.