This paper investigates the drivers and inhibitors of Internet privacy concern. Applying the Multidimensional Development Theory to the online environment, we identify the important factors under four dimensions—i.e., environmental, individual, information management, and interaction management. We tested our model using data from an online survey of 2417 individuals in Hong Kong. The results show that the factors under all four dimensions are significant in the formation of Internet privacy concern. Specifically, familiarity with government legislation, Internet knowledge, benefit of information disclosure, privacy protection, and social presence reduce Internet privacy concern, while individuals’ previous privacy invasion experience, risk avoidance personality, and sensitivity of information requested by websites increase Internet privacy concern. We conducted an analysis of unobserved heterogeneity to confirm the significance of these factors. A follow-up moderation analysis shows that the individual factors (i.e., previous privacy invasion experience, risk avoidance personality, and Internet knowledge) moderate the effects of the information management factor (i.e., information sensitivity) and the interaction management factors (i.e., privacy protection and social presence). The findings provide an integrated understanding of the formation of Internet privacy concern.