The author discusses the criteria of instinctive behavior[long dash]it is behavior that is unlearned, that is characteristic of the species and that is biologically adequate. Reflexes are also unlearned but are simpler, more specific and more variable than instincts. Instincts may be looked upon as an inherited coordination of reflexes. Modifications in instinctive behavior after the instinct has first appeared may result either from maturation or from conditioning. Sublimation is a form of instinct modification in the human individual. In all instinctive behavior there is pleasure and satisfaction associated with inherited muscular and glandular functioning.