The aim of this action research project was to investigate students' social preferences and pro-social interactions in a multiage, high school classroom in order to better understand how to group students to maximize learning and collaboration. According to many educational experts and previous inquiries, mixed-age learning groups introduce numerous social, emotional, and academic benefits into the classroom setting but this research has been predominantly conducted at the primary school level. In response, the specific focus of this research project was to examine how and if mixed-age grouping in a high school classroom affects student preference for peer collaboration over independent work when given a choice, and their collaborative relationship with their peers. This research was carried out within a mixed-age social studies classroom during the spring of 2014. Data was collected qualitatively through student interviews and in-class observations. Additionally, quantitative methods was used to gather data on student social preferences and relationships within collaborative groups. Data collection methods were designed by this researcher and carried within a semi-controlled, naturalistic, class periods. The following are appended: (1) Data Collection Plan; (2) Student Interview Questions; (3) Student Survey; (4) Anecdotal/Observation Log; and (5) Student Choice and Preference Log.