According to Gilbert Ryle, improvisation is a basic feature of ordinary action. In this paper, we take this idea seriously. Action is improvisation, in that it is situated: It is shaped by attentive responses to environmental circumstances. This is a crucial aspect of agency. However, it is neglected by causal theories of action (Bratman; Mele) and only partially addressed by Thompson’s process-oriented theory. By resorting to Kant’s theory of judgment, we argue for understanding action performance in terms of improvisational shaping (...) of action in situ. The focus on improvisation points to a situated kind of practical rationality entailing the reciprocal shaping of intention and action instead of the ordinary instrumental kind of rationality of action as unidirectionally determined by intention. (shrink)