Careful analysis of the temperature dependence of the hole mobility in poly (methylphenylsilane) indicates that the functional dependence is between an Arrhenius law and a In mu is-proportional-to T-2 law as predicted by a model of disorder-controlled hopping. This is attributed to the superposition of disorder and polaron effects. A method is presented for separating the two contributions. The evolution of time-of-flight photocurrent transients with decreasing temperature is consistent with the disorder parameter derived from the temperature dependence of the mobility.