Collision induced transitions between rotational levels of methanol have been investigated by steady state microwave double resonance, in order to study collisional excitation mechanisms for methanol in the interstellar medium. Experiments are described on pure CH3OH and on dilute mixtures of CH3OH with excess He and H2, for various four level systems of astrophysical interest. For pure CH3OH, the results are qualitatively consistent with dipolar selection rules, ΔJ = 0, ± 1 and Δk = 0, ± 1, but certain aspects of the quantitative analysis are unexplained. For collisions of CH3OH with either He or H2, the collisional transition rates decrease relatively slowly with ΔJ. In the collisions with He, parallel Δk = 0 collisional transitions occur about four times more frequently than perpendicular Δk = ± 1 transitions, whereas in collisions with normal H2, Δk = 0 transitions are approximately twice as frequent as Δk = + 1 transitions.