With the aid of a hot-wire anemometer, the mean velocity distribution of the incompressible, turbulent, plane wall-jet has been examined in some detail. As previously reported, this fully developed boundary layer belongs to the class of self-preserving flows. Over the entire range of experimental conditions, a single velocity scale $(\overline {U}_m)$ and a single length scale (δ) seem to correlate all the velocity data. Further, it is shown theoretically that δ must vary as x, and $\overline {U}_m$ must vary as xa over this range. The exponent a has been empirically determined as -0.555. Values of the Reynolds shear stress, which are proportional to $\overline {u} \overline {v}$, the Boussinesq exchange coefficient ε, and the shear stress at the wall have been evaluated. The Reynolds number based on the maximum velocity and the thickness of the boundary layer varied from 22,000 to 106,000.