According to Frege, judgement is the ‘logically primitive activity’. So what is judgement? In his mature work, he characterizes judging as ‘acknowledging the truth’ (‘Anerkennen der Wahrheit’). Frege’s remarks about judging as acknowledging the truth of a thought require further elaboration and development. I will argue that the development that best suits his argumentative purposes takes acknowledging the truth of a thought to be a non-propositional attitude like seeing an object; it is a mental relation between a thinker, a thought, and an object, namely a truth-value.