In this overview, we examine action research and curriculum development from the last 50 years in various national and educational settings. Both action research (AR) and curriculum development are explored in diverse ways, depending on academic traditions and national contexts and languages. Hence, curriculum is differently conceptualized in, for example, English vis-à-vis Nordic traditions. The concept of curriculum development may, in the tradition of action research as an orientation toward educational change, incorporate both planned and unplanned student learning and practices of teachers. Several international scholar contributions as well as 50 journal articles from all around the world are explored. The point of departure, is however, in the Nordic traditions and understandings of curriculum development and AR. In other words, we are partly “coming from the side” when exploring literature, not mainly in our first language (Swedish), but in English. In the first part, we start in the early 1970s to show how curriculum development is embedded within an action research tradition with a strong emphasis on change and teacher experiences and engagement. We shed light on how curriculum development is a collaborative practice (in AR traditions in, for example, the United Kingdom and the Nordic countries) as well as an exercise of authority (in AR used by educational policymakers in Sweden) and as part of a global “practice turn.” In part two, we turn to 50 articles from 2000–2020, found in one data base and one research journal, to scrutinize the explicit relation between “action research” AND “curriculum development.” The analysis revealed three descriptive themes, as well as three underlying questions in the AR community, of what contributes to curriculum development. The themes—and questions—are: (a) Transforming the content in programs and courses (the “What”), (b) Professional learning and development (the “Who”), and (c) AR as an approach for curriculum development (the “How”). Teachers are still, as in the 1970s, the key agents and owners of the process in many of these studies. However, there are examples of AR being used to govern teachers’ professional learning and change their teaching approaches, and to implement specific curriculum changes. Policies and discourses of sustainable development have a significant impact on the chosen topics of curriculum development all over the world. Is this a change in the professional or the political dimension of action research? Maybe both. One can ask, whether the professional autonomy is empowered or not, when the issues, underpinning the development work, have their origin in the society rather than in the actual classroom practice in the local site. Is there room for teachers’ critical voices and own queries? Education has, however, to respond to global and local questions and dominant challenges for all citizens. Researchers and teachers responding to this situation, by using action research for curriculum development, become an important and necessary part of the global strive to engage in social and environmental problems.