Understanding the “intentionality” of mental phenomena is widely regarded as a key problem in philosophy of mind. Franz Brentano (along with his students, especially Edmund Husserl) is widely credited with bringing intentionality to philosophers’ attention. In early treatment by the Brentano school, intentionality is at least nominally understood as executed, brought about, or achieved in mental acts. And in the early 20th century, historians of psychology regarded this “act conception” of intentionality as integral for understanding the phenomenon. Yet the secondary literature on Brentano and Husserl provides no clarification of mental acts as acts, and in contemporary philosophy, we have no workable account of what it could mean for inten...