Social networks provide traditional concept mapping of new opportunities for concept construction with grouping, social interaction, and collaborative functions. However, little effort has been made to explore the effects of social network–supported concept mapping compared with traditional individual concept construction. This paper explores the effects of social network–supported group concept mapping (SCM) activity and compares them with the effects of individual concept mapping (ICM) activity. A platform named CoCoing.info (http://cocoing.info) is utilized to examine the SCM and ICM activities under three studies, which drove the following research questions: (1) Do map structure (i.e., propositions, hierarchies, examples, cross-links, and scores) and mapping activity (i.e., map modification period and frequency) differ between ICM and SCM in students on specialized courses? (2) Do map structure and mapping activity differ between ICM and SCM in students on general education courses? (3) What are the effects of group size on SCM? In study I, four classes are selected to ensure a strong social network learning environment control. On the basis of study I, study II extends the controlled environment within an open social networking environment with a total of 1106 SCM maps and 569 ICM maps to produce an improved overview of concept mapping. The findings of studies I and II are consistent, demonstrating that the students constructed more comprehensive concept maps and had a higher modification period and frequency with SCM than with ICM, which indicates that in a social network learning environment, SCM is favorable to ICM. Study III considers each participant’s contributions to identify an optimal group number. The results of study III indicate that groups with two to seven members perform better than larger groups. Overall, the findings demonstrate the benefits of integrating concept mapping with social networking for student learning outcomes.