The article presents a proposal of explanation what practical rationality is, how it works and what are its criteria. In order to define practical rationality, the author starts from the general characteristics of reason, and then in the realm or reason activity distinguishes practical rationality from theoretical rationality. The necessary conditions of practical rationality are presented, as well as its standing between freedom and values. Next, the sources and nature of practical reasons are characterized, as well as their relation to (...) values and desires. The problem of practical syllogism is briefly commented on. In the final part of the article the author proposes five criteria of practical rationality. (shrink)