Regulation involves regulating our level of arousal in terms of how calm or excited we are. It is a process manifested in two ways, outwardly or inwardly. Outwardly, expressed as feelings or emotions (calm, angry, or concerned) and inwardly expressed as the physiological or bodily response (faster heartbeats or tense muscles, or shallower breath).

The ability to regulate our arousal level begins to develop as an infant and it provides the foundation that later allows us to self-regulate to information in our environment depending on what is useful and what is not. Self-control is a core competence that enables the ability to form relationships with others.

An infant has a limited capacity to self-regulate, for instance, an infant can be overwhelmed by the external environment and as a result, may simply fall asleep. Alternatively, when the infant has an unfamiliar or uncomfortable feeling, whether hunger or other discomforts, the infant will cry signalling that something is wrong. In such a circumstance, if the parent/caregiver picks up the infant and makes eye contact or soothes them, then the infant begins to calm down. This is referred to as co-regulation.

Co-regulation is a form of coordinated action between participants that involves the continuous mutual adjustment of actions and intentions. It is not a one-way process but involves exchanges with each participant adjusting their responses based on the response of the other.

Self-regulation is influenced by external factors such as the environment and interaction with others or internal factors such as temperament while co-regulation involves tuning responses towards a common purpose for instance finding ways to resolve upsets from stress to return to balance.