If we are to have knowledge then we must be justified in what we believe. How should we understand the justification component of knowledge? According to Agrippa’s trilemma, there are only three alternatives in this regard, and none of them are particularly appealing. The first alternative is to regard one’s belief as being justified by nothing at all. The second alternative is to regard one’s belief as justified by a further ground. But that option seems to lead to an infinite regress. Finally, there is the third option of allowing circular justifications. We consider three responses to Agrippa’s trilemma. The first option is infinitism, which holds that an infinite chain of grounds can justify a belief. The second response is coherentism, which holds that a circular chain of grounds can justify a belief. The third option is foundationalism, which holds that there are some grounds which do not require any further support, and which can thus act as foundations for the beliefs that rest upon them.