This study investigated whether two educational strategies, providing material and active adult support during play, promote pretend play quality in a group of preschoolers. The sample consisted of 101 preschoolers (50% females; mean age at t1= 43.02 months, SD= 5.94) from 14 Swiss educational play groups. These were randomly allocated to the experimental conditions: "material" (n=4 groups, n=35 children), "play tutoring" (n=5 groups, n=32 children), and "treatment as usual" (control; n=5 groups, n=34 children). Children's and adults' behavior during six play sessions, each lasting 30 minutes, was videotaped. Children's play activities, social pretend play quality (SPPQ) and adults' level of active pretend play support, were assessed using standardized observation tools. Research Findings: Material and play tutoring groups showed significantly higher frequency of pretend play than the control group. Regarding SPPQ, the material group scored significantly lower than the play tutoring group, but significantly higher than the control group. Additional analyses showed that differences in SPPQ between the control and material condition can be fully explained by adults' active play support. Practice or Policy: The results suggest that providing roleplay material stimulates children to engage in social pretend play, but adults' play support increases the quality of social pretend play.