Similarity solutions of the boundary-layer equations representing the flow of jets in an external stream and tailored pressure gradients were obtained. These solutions apply to jets in coflowing and counterflowing streams. A number of analytical solutions not previously published were obtained. Of particular interest are the solutions for small-increment jets which imply that a Gaussian velocity profile exists far downstream from the origin of the jet, even in arbitrary pressure gradient. The solutions were extended to turbulent flow using the hypothesis of a constant eddy viscosity, which in turn, was modified to account for intermittency. The theoretical predictions were compared with the measurements of Gartshore in self-preserving wakes and the agreement between theory and experiment is good.