Within the identity literature, self and identity are often used as interchangeable terms. By contrast, in Self-Determination Theory (SDT; Ryan & Deci, 2003) both terms have a differentiated meaning and it is maintained that identities may vary in the extent to which they are congruent with the basic growth tendencies of the self that are fueled by the basic psychological needs for autonomy, competence, and relatedness. Specifically, the level of congruence between identities and the self is said to depend on (a) the motives underlying one’s identity commitments (i.e., pressure versus volition) and (b) the content of the goals defining one’s identity (i.e., extrinsic versus intrinsic). It is argued in SDT that both the motives and the goals behind one’s identity are important for optimal functioning because of their linkage with basic need satisfaction. This chapter (a) compares the SDT view on identity development with prevailing models of identity formation, and with constructivist models of identity in particular, and (b) reviews research relevant to the idea that identities need to be congruent with the self in order to foster well-being and adjustment
