In Bowlby’s scheme, behaviour that predictably results in attaining or maintaining proximity to or communication with some other preferred individual is called “attachment behaviour”. Such behaviour is particularly likely to occur under conditions of fear, uncertainty, fatigue, etc. Over the first half-year of life attachment behaviour becomes organised into a goalcorrected behaviour system. A “behaviour system” is a set of alternative behaviour patterns with some common causal factors leading to an out­ come that normally decreases the activation of the system in question (Baerends, 1976). In this case, the behaviours are such as promote proxim­ ity to or communication with the attachment figure. A complementary parental behaviour system is also postulated.