Survey data were collected from 445 part-time transportation workers to test three sets of competing hypotheses about primary and secondary part-time workers that were developed from Partial Inclusion theory (Allport, 1933), Investment Model theory (Farrell & Rusbult, 1981), and the Part-time Work Arrangements perspective (Feldman, 1990). The Investment Model constructs explaining job satisfaction, organizational commitment and turnover intent received the most support. However, the part-time work arrangements perspective also received some support as there were significant differences in organizational commitment and turnover intentions between primary and secondary part-time workers. The application of Partial Inclusion theory to the part-time worker subgroup context was not supported.

INDEX WORDS: Part-time Employment, Investment Model theory, Partial Inclusion theory, Part-time Work Arrangements, Job Satisfaction, Organizational Commitment, Turnover Intent, Transportation Industry.