A common form of argument in philosophy claims that some philosophical thesis, T, generates an infinite regress, whereupon the reader is supposed to see that T must therefore be rejected (see Chapter 2). Such arguments often prove controversial, and the controversy usually centers on whether the infinite regress in question is vicious or benign. In this chapter, I offer an account of when an infinite regress is vicious, which I deploy to assess the six infinite regresses discussed in Chapter 2.