The first direct determination of the propagation speed of a lightning return stroke lowering positive charge to ground has been made. This stroke was the third of eight otherwise negative strokes in a triggered lightning flash initiated at the Kennedy Space Center, Florida. Two independent optical systems, one photographic and the other photoelectric, yielded common recordings for the third and fourth strokes; the respective two-dimensional return stroke propagation speeds were 1.0 vs. 0.93¿108 m/s for the positive (third) stroke and 1.0 vs. 1.0¿108 m/s for the fourth stroke. Using fast electric-field data, we estimate the positive stroke peak current to be 21 kA. Photoelectric data only yielded propagation speeds of 1.4, 1.6, 1.2, 1.3, 1.0, and 0.90¿108 m/s for the first, second and fifth through eighth return strokes, respectively. All propagation speeds were evaluated over 850 m of channel near ground and have an error estimate of 10--15%. For this positive stroke, we found a return stroke propagation speed typical of negative strokes. Whether positive return strokes, in general, travel at typical negative return stroke speeds must await future measurements.