The constructivist metaphor is fundamentally based on the idea of an intentional cognizing agent who builds mental structures that allows him-/herself to cope with the world, that is, the mental structures are selected in terms of their viability rather than the quality of their correspondence with an outside world. Because of the tight link between intentionality and agency, constructivism is unable to explain a range of phenomena that have come to be known as the abyss between plans and situated action, theory and practice. In this chapter, I use these two examples from my empirical work among research scientists as the data for a reflection about the source of the abyss between plans and situated action, leading me to theorize the gap.