This study develops a classification model to predict social actors' co-innovation behavior in social product development (SPD) networks based on motivational differences. The study first identifies motivations for actors to continuously participate in co-innovation activities. Then, three discriminant functions are developed and cross-validated to classify actor groups, based on their level of willingness to participate in three types of behaviors: ideation, collaboration, and socialization. The results indicate that financial gains, entrepreneurship, and learning are significant predictors of ideation behaviors. Enjoyment and learning are strong indicators of collaboration, whereas networking, enjoyment, and altruism are most strongly related to socialization behaviors. These findings highlight three classes of SPD actors (Ideators, Collaborators, and Networkers) based on motivational differences. These classes provide a theoretically parsimonious model to predict the co-innovation behaviors in SPD and highlight the importance of platform design to appeal to different classes of potential contributors.