This paper presents some remarks on the theory of hybrid activities. Analysis of relevant texts indicates that at present there is no real theory of hybrid activities. Interpretations and definitions of hybrid activities differ to some extent and certain important features are missing. For example, some authors opine that hybrid activities consist of simultaneous military and non-military operations. This opinion is not necessarily true as non-military activities can precede military activities. Monitoring this phase of hybrid activities is particularly important. The so-called “crisis management” covers (from the viewpoint of praxeology) a too narrow area.