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. Social pretend play is discussed as a highly important activity for children's positive development in theory and empirical studies alike (Smith, 2010). Promoting it is therefore a desirable educational aim. Importantly, the quality of social pretend play, as opposed to its mere quantity, is seen as the crucial factor that is linked to a desirable impact on children's development (Bodrova et al., 2013; Vygotsky, 1978). In the discussion of educational pathways to promote children's social pretend play and-to go even further-their positive development, the focus should be on the question of what effectively promotes the quality of social pretend play. One potential educational strategy is to provide roleplay material as a stimulus in children's play environment for social pretend play. It is argued that the construction and arrangement of children's proximate physical environment affects their play type. This may differ according to the current activity setting and the play materials available (Brown & Briggs, 1989; Morgante, 2013; Petrakos & Howe, 1996). Trawick-Smith et al. (2015) define two functions of play material: (1) to be a stimulus for play and (2) to focus the attention of a group of children. This may suggest that providing thematically structured roleplay material could encourage a group of children to engage jointly in social pretend play (frequency and quality). Findings from some previous studies cautiously support the hypothesis that providing specific roleplay material (e.g., theme-related items) may promote the frequency of pretend play during play sessions (e.g., McLoyd,