In this article we discuss a possible interpretation of the interference effect. We suggest that the Stroop interference is a result of Task Control process. Experiments (N = 90) test a hypothesis that interference effect appears when participants have a capability to make a mistake, i.e. choose an answer for an irrelevant dimension of Stroop stimuli. Data shows that lack of such capability leads to decrease of interference effect because cognitive control over irrelevant task is reduced. Refs 39. Figs 2. Tables 2.