We predicted that short-term training of executive control would improve both cognitive control itself (Hypothesis 1) and general fluid intelligence (Hypothesis 2). We randomly assigned 120 high school students to the experimental and control groups. The former underwent a 14-day training of four executive functions: interference resolution, response inhibition, task switching, and goal monitoring. The latter did not train anything. The training significantly improved cognitive control and IQ. The control group also improved their IQ scores but gained less than the experimental one. However, the amount of IQ scores enhancement did not correlate with the majority of indices of the training effectiveness, thus justifying the supposition that such enhancement resulted from the general effect of participation in the training rather than from the improvement of executive functions underlying Gf.