Style of activity is determined by a number of properties (morphological, physiological, psychological) - not only by typological properties of the nervous system. It is more proper therefore to define activity style as a tactical system of ways of performing particular tasks and not as a way of performing particular acts. Styles of activity also do not get developed as a means of efficient performance. Relations between the style and efficiency are rather complicated, and there may be cases when styles, developed in accordance with typological dispositions, are counterproductive from the efficiency point of view. The data are given which show that styles may have variants, i. e. there may exist substyles.