Prosocial behaviors (e.g., sharing, helping) are important for adolescents' academic and social-emotional wellbeing and can be predicted by students' adoption of prosocial goals. Due to the recent uptick in experiences with learning online for adolescents, understanding what prosocial behaviors look like for students within this context, as well as identifying students who do or do not have goals to exhibit these prosocial behaviors, have increased in importance. The purpose of this study was to develop and validate a new measure, the Prosocial Goals in Online Learning Instrument (P-GOLI), which could be used to determine whether a student has prosocial goals when they are engaged in learning online. Phase 1 (Development and Validation) included the initial development of P-GOLI items based on a review of the literature, expert reviews (n = 3), cognitive interviews (n = 5), and a pilot test (n = 18). In Phase 2 (Continued Validation), the instrument was administered to a larger sample of the population (N = 123), along with others instruments to support construct validity. Exploratory factor analysis was conducted and the P-GOLI was found to have three factors: Interactive, Reflective, and Problem-Solving prosocial goals when learning online. Implications, limitations, and next steps for the P-GOLI and this novel construct are described. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]