This study proposed an alternative model specification to increase accuracy of conceptualization of the definition of customer engagement and provided theoretical justification for the model in specific social media contexts. The proposed model is a formative construct based on theoretical contexts and observational data. The construct comprises six formative first-order dimensions, namely “influencing behaviors,” “participation in activities,” “customer knowledge sharing,” “feedbacks,” “helping other customers,” and “customer-to-customer interaction.” The study findings offer a basis for identifying indicators of distinct dimensions in the proposed construct. Three models with different conceptualization specifications were estimated and subsequently compared using survey data.