There is great concern by teachers, school administrators and parents regarding the increase in the number of preschool-aged students who exhibit challenging behavior in early childhood settings (Benedict, Horner & Squires 2007), need for early intervention procedures that focus on young children who may be at risk for developing patterns of challenging behavior is evidenced. Positive Guidance principles which are similar to Positive Behavior Support principles are often incorporated into preschool programs, however there has been relatively little attention given to Program-Wide Positive Behavior Support (PWPBS), as defined by PBIS, in preschool settings (Hemmeter, Fox & Broyles, 2007). Research has also documented that early intervention programs, as well as complementary alternative therapies, have been successful in providing children with opportunities to develop age appropriate academic, physical, social, and behavioral skills (Boso, Emanuele, Minazzi, Abbomonte, & Politi, 2007). Complementary alternative therapies include art, music, movement or horticultural activities. The activities suggested for this study incorporated the use of plants and/or plant materials in a variety of non-invasive activities that provided an opportunity for everyone in the class to participate. Twenty-one students and six adults from two preschool classrooms participated over a 16 week period. There were four students in each class identified as presenting challenging behaviors. These students were consistently observed for behavioral performance. In addition, two randomly chosen students from each class were observed. Peer interactions and task engagement observational data was collected and analyzed along with qualitative data in this mixed methods investigation. Data collection methods included behavioral checklists, direct and indirect observations, teacher interviews, surveys and classroom artifacts. The researcher sought to uncover if horticultural activities would encourage positive peer interaction and task engagement. These activities were modeled by the researcher who was not a horticulture therapist. The results were promising. It was determined through the course of the study that, task engagement and positive peer interactions increased after the implementation of the horticultural activities. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]