We present measured current, luminosity, and electric and magnetic fields for a rocket-triggered two-stroke flash. The first stroke lowered negative charge to ground and the second stroke lowered positive charge via the same channel. A triggered positive stroke is a very rare event. The measured negative return stroke peak current was -11 kA and the positive +5 kA, with the total charge transfers being -1 C and +24 C, respectively. Electric field measurements at 120 to 520 m indicate that the negative and positive dart leader charge densities were approximately constant with height, -7.2 ¿ 10-5 C m-1 and +5.5 ¿ 10-5 C m-1, respectively. Magnetic field measurements indicate a negative leader current of -1.9 kA and a positive leader current of +400 A. Negative and positive dart-leader speeds are estimated to be 2.7 ¿ 107 m s-1 and 0.7 ¿ 107 m s-1, respectively. Negative and positive return stroke speeds are estimated to be 1.6 ¿ 108 and 0.92 ¿ 108 m s-1, respectively.