In this chapter, we propose to analyse understanding as a synthetic activity of grasping the meaning of a sign and articulating a series of signs. First, we will show that understanding responds to a ‘grammar of success’ when it looks to what has happened and been resolved; understanding responds to a grammar of intention and effort when it looks to the aim of meaning. Secondly, we aim to show that while interpretation is a form of understanding (mediate and reflexive), not all understanding, when spontaneous, is interpretation. Thirdly, it is a question of overcoming the epistemological antagonism between explanation and understanding by broadening their spectrum beyond the psychological model and the nomological-deductive model. Finally, it is a question of showing that not all understanding is an application. Understanding is an application only when meaning is grasped with a view to adapting it to a concrete, present situation.