In Valiant [11] and Schnorr [9], concepts of "functional self-reducibility" are introduced and investigated. We concentrate on the class NP and on the NP hierarchy of Meyer and Stockmeyer [7] to further investigate these ideas. Assuming that the NP hierarchy exists (specifically, assuming that $P \stackrel{\subset}{+} NP = \sum^{P}{1} \stackrel{\subset}{+} \sum^{P}{2}$ we show that, while every complete set in $\sum^{P}{2}$ is functionally self-reducible, there exist sets in $\sum^{P}{2}$ which are not functionally self-reducible.