Outcomes of a project or a policy often differ from expectations. We call such discrepancies “implementation gaps”. Reasons for these gaps and for their persistence are worth serious study; such study should be a good entry point for developing an implementation science. We wrote a concept paper for a special session at IDRiM 2022; five discussants led a discussion of the paper and of challenges in developing an implementation science. The present paper represents our updated perspective after further reflection and the special session discussions. According to our perspective, the fundamental challenge in describing implementation gaps and then moving toward an adaptable and expansive implementation science is to account for the number and diversity of actors in implementation activities. Different actors have different roles, different capabilities, and powers; their knowledge about the situation is different, and their concerns and perspectives are also different. We begin by considering innovative approaches to describing and characterizing implementation gaps. We construct a model implementation story “a furniture nailing story,” based on real experience in Japan following lessons learned from the Great Hanshin-Awaji earthquake of 1995. We also offer a model implementation failure story “a snowstorm story.” In providing detail, attention to the diversity of actors is key; further analysis begins with a deeper characterization of actors and their relationships, influences, and interactions with each other. We proceed to discuss steps toward an implementation science. We consider three aspects of science: 1) description: characterizing gaps, classifying them, and making classifications useful; 2) designing and testing: finding models for implementation processes and seeing how they work; 3) prediction: anticipating and preparing for challenges and opportunities in implementation. Finally, we consider possibilities for learning from experiences in other fields and recommend modest attempts to develop new dialogues with “prospective neighboring disciplinary communities.”