The objective of this dissertation was to determine whether there were significant differences in the mean scores in vocational maturity between male and female students, between students who believe their career development is controlled mostly by external factors and those who believe that they control their own career development, and between disadvantaged blacks and Puerto Ricans. The sample for the study consisted of 160 randomly selected black and Puerto Rican ninth graders with 80 internally controlled students assigned to one of four equal groups of 20, and 80 externally controlled students assigned in a similar fashion. All subjects were given Rotter's Internal External Control Scale to determine locus of control and Crites' Attitude Scale of the Career Maturity Inventory to measure the noncognitive aspect of vocational maturity. The results suggested that ethnicity and the interaction of sex and locus of control had a differential effect on vocational maturity of black and Puerto Rican inner-city youth. It could not be shown that sex, locus of control, and the interaction of sex and ethnicity, locus of control and ethnicity, and sex, ethnicity, and locus of control per se accounted for differences in vocational maturity. (Author/AM)