Social factors in the classroom (such as interactions with peers and teachers, talk, observation of others, and presence of peers and teachers) influence engagement, but little is known about the sequence or timing of these social factors with engagement. In this observational study of 12 preschoolers, ages 2-5 years, the influence of the timing of social factors on engagement was examined in depth, using sequential analysis techniques. Children’s talk to teachers and teacher presence encouraged initial engagement in activities. Teacher and peer presence, talk to and from peers, and self-talk encouraged continuing, sustained engagement, while teacher talk to children led to disengagement. Children's observations of peers in a new activity led both into and out of engagement. Teacher interactions with children function as a bridge into and out of engagements but did little to sustain engagement, whereas peer interactions and self-talk sustained ongoing engagements. Implications for encouraging engagement in preschool classrooms are considered. (Contains 6 tables and 1 figure.)