We discuss the stability of solutions to a class of nonlinear third-order ordinary differential equations arising in the viscous flow over a nonlinearly stretching sheet. In particular, we consider solutions over the semi-infinite interval [0, ∞). These results complement the available existence and uniqueness results in the literature. We find that, in general, there is one stable solution branch and one unstable solution branch. Furthermore, it is observed that the stable solution becomes more stable with an increase in the nonlinearity due to the stretching sheet, while the unstable solution branch becomes more unstable given such an increase in the nonlinearity. The stable solution is the physically meaningful solution.