Teachers’ work lives unfold over time in the dynamics of stability and change. Educational innovations make up a particular category of changes with particular consequences for teachers, their career, and their professional development. Starting from a generic definition of educational innovations, this chapter seeks to clarify what typifies innovations in education and how their implementation relates to teacher professionalism. Taking an agentic perspective, the central role of teachers’ contextualized sensemaking in their dealing with innovations is highlighted. Furthermore, it is emphasized that educational innovations do not simply aim for change per se, but rather envisage changes that claim to be an improvement. This inevitable normative dimension in innovations further complicates the implementation process beyond mere instrumental concerns of effectiveness and feasibility. The interplay of professional sensemaking, contextualization, and normativity is further exemplified by zooming in on two phenomena in educational innovations: resistance and configurations. However, rather than considering resistance and configurations as problems or failures in the implementation, research provides evidence to understand both phenomena as expressions of teachers’ agency and professionalism through the concept of interpretative negotiation. The final section summarizes and brings together the argument. Firstly, it is concluded that implementation practices can be understood as the actual, contextualized answer to a set of essential questions or issues: normative, political, strategic, creative, effective, and explanatory. Secondly, it presents a three-dimensional framework of dualities that are constitutive for actual implementation practices: stability-change, agency-structure, and teacher development-school development. Both are conceptual tools that can heuristically help researchers in unpacking and elucidating the process of educational innovations. Similarly, they can support practitioners in making insightful judgments and choices to design implementation practices and to monitor and possibly modify them over time.