We explored two questions in two empirical studies. In the first study we wanted to find out whether we could describe the interactions between New Product Development (NPD) and Operations by using a generic theory of change management and interventions. In the second study we explored such interventions during implementation and wanted to find out to what extent these interventions followed the theories of change. Some of the interactions are interventions from NPD to Operations in order to change the work of Operations. We found that these interventions and intended changes fit the theories of change management quite well. This means that the change literature gives good insights into the causes of success and failure of these interventions and could mean that, in some respect, we can apply the knowledge of these theories of change management and interventions to the field of NPD. This insight provides a new and additional perspective: NPD to be seen as a process that uses interventions to facilitate, or provoke, change within operational processes. We see too much attention paid to the project management methods and 'hard' theories, for example rationality, control, hierarchy, planning, predicting and prescribing. There is good reason to add the more 'soft' theories of change to NPD practice, with extra and explicit attention to learning, trial and error, monitoring, tell and sell, empathy, and co-operation. NPD practitioners are also very much focused on the product and less (or not at all) on the actual changes that have to take place in production (Operations) related to the implementation of these processes. For successful implementation interventions need to be tuned towards the receiver. The interventionist (i.e. NPD practitioners) must be aware that there is a range of choice if different intervention strategies in order to tune their intervention efforts more effectively towards the receiver. In order to be able to do this, NPD practitioners, as well as the people from Operations, need to become skilled in using a generic theory of intervention and change, such as the one described in this paper, during their interactions.well as the day-to-day operational processes. The focus of this paper will be on the main stream of new products like line extensions, next versions, etc. that have to be implemented in operational processes. These dayto-day new products are not believed to be disruptive in any sense. Excluded from this research are breakthrough products. For this stream of new products the interface between NPD and Operations a vital link. In order to be effective in their innovative efforts, companies need to understand all the interactions between NPD and Operations. This is not always the case. INTERVENTIONS IN EXISTING OPERATIONAL PROCESSES109