This project promotes collaborative learning among students taking introductory Computer Science (CS) courses through an online social learning environment, called PeerSpace. PeerSpace is based on the fundamental idea of the successful Emerging Scholars Program, a peer-learning program that enhances student learning by promoting strong peer support, both academically and socially. PeerSpace consists of two main components: the social network component and the peer-learning component. The social network component provides students with online collaborative tools for convenient synchronous and asynchronous online interactions on course related topics as well as social topics. The student-centered pod membership and the pod-to-pod friendly competitions are used to give students a sense of belonging to the learning community, and to encourage the building of peer support networks. The peer-learning component is a set of carefully designed peer collaborative exercises organized in a novel way to emphasize peer collaboration by integrating popular peer learning techniques in computer science education such as group discussion, peer code review, and student self-reflection. These peer collaborative exercises encourage students to help and support each other academically within the established social environment, deepening students' understanding of course material and enhancing students' motivation, persistence, and passion towards their study. The goal of PeerSpace is to promote peer collaborative learning in introductory CS courses by providing carefully designed peer collaborative exercises within a friendly, peer-supportive online social network environment, and to facilitate the building of peer support networks that lasts throughout and beyond the introductory CS courses.