Self-regulation is the ability of a population to change automatically in response to changes in living conditions through regulatory mechanisms. Regulatory mechanisms that control changes in population size and biomass act mainly through changes in the metabolism of the individuals that make up the population, alter the rate of reproduction and attrition, and ensure the existence of a species, population or individual under certain conditions.

The ability of biological systems (at any level of life organisation) to automatically establish and maintain vital functions at a certain, relatively constant level. The controlling factors are formed in the biosystem itself. The impetus for mobilising mechanisms to restore the normal functioning of a biosystem is a deviation from its stable level. Self-regulation mechanisms are very diverse (depending on the specific level of organisation of living matter). They are usually based on similar principles, primarily the principle of feedback. Examples of self-regulation at the level of supra-organisational systems (populations, biocenoses, biosphere) are: regulation of the number of populations, the sex ratio in them, the ratio of fertility and mortality, homeostasis of ecosystems, etc. Self-regulated biological systems include systems in which the regulated parameters are constant and the results of regulation are stereotyped, as well as adaptive systems (self-regulating, self-learning) that automatically adapt to changing external conditions. Self-regulation is one of the fundamental characteristics of living systems.