Businesses across the world consider gamification as a key customer engagement marketing (CEM) strategy. Effective gamifications, meaning that the gamification results in enhanced customer engagement (CE) and business performance, are plentiful but are accompanied by an even larger number of ineffective gamifications. In the context of an overarching CEM-model describing the chain of effects among CEM initiatives, CE, and business performance, two research objectives are addressed. The first research objective is related to the development of an iterative multi-stage process CE conceptualization. This conceptualization, which is at the heart of CEM, adds to the existing literature by integrating seemingly opposing CE definitions and frameworks. The second research objective explores gamification as a CEM initiative in detail. It is conjectured that gamification influences CE via the resource integration process, thereby providing insight in the gamification-engagement mechanism. Moreover, a set of gamification design principles drawing upon recent advances from service design theory and information systems research is put forward. This chapter ends with a set of research questions to stimulate further research in the areas of CEM, CE, and gamification.