The sources of multidimensionality found in several different forms of a licensure examination were studied. The relationship between one source of multidimensionality, differential item functioning (DIF) (or factors producing DIF), and content characteristics was explored in an attempt to isolate aspects of training or curriculum that could accound for the causes of multidimensionality in real data. A non-parametric approach for assessing unidimensionality developed by W. Stout (1987) was used to evaluate the dimensionality of several forms of a 300-item Rasch-based test used to license professionals in a health care profession. Quasi-random samples of 2,000 first-time candidates were selected for each of the 4 forms. The four forms were demonstrated to be multidimensional. The source of the multidimensionality could not be attributed to the presence of a large number of passage-like cases with associated multiple items. A second dimension was identified as the source of the multidimensionality through the magnitude of eigenvalue differences and the successful construction of part-forms made unidimensional by removal of items loading heavily on the second factor. An association between the second factor and items flagged for DIF was demonstrated. Items that loaded heavily on the second factor and were often flagged for DIF spanned content that involved knowledge and recall of physiological needs versus an evaluation/analysis of psychosocial needs. Six tables present study data, and there is a 16-item list of references. (SLD)