It was hypothesized that individuals vary in their general environmental orientation: some are oriented to the internal and some to the external environment. We next predicted that this difference would be reflected in the location of those characteristics by which such persons define their identity. A sample of 150 persons judged the location of a set of 22 identity characteristics. These characteristics were rated on importance for self and then correlated with personality tests assumed to assess individual differences in environmental orientation. Authoritarianism, Snyder's self–monitoring, and Rotter's external locus of control were taken as measures of an external environmental orientation; Laird's locus of causal attribution and Sampson's measure of internal orientation (IO) were taken as measures of an internal environmental orientation. With all scales but Rotter's, strong support for the predictions was found: i.e., authoritarianism and self–monitoring were positively correlated with externally located identity characteristics; a dispositional attributional bias and the IO were positively correlated with internally located identity characteristics. These findings were discussed in terms of a process of identity mastery.