Numerous data of long-term investigations of weak agents on morphogenetic processes in invertebrates (regeneration of planarians, Dugesia (Girardia) tigrina and postembryonic development of insects, the grain beetle Tenebrio molitor) have been analyzed. Weak physical and chemical factors were used: electromagnetic radiation, static, alternating, and combined magnetic fields, and low concentrations of solutions of neuropeptides. Some common features of the influence of weak factors on morphogenesis were found, namely, the instability and the opposite direction of the effect. The dependence of the effects on external conditions and the dynamics of physiological functions of objects was established.