The purpose of this study was to develop a core HIV/AIDS knowledge assessment (CHAKA) for students enrolled in counseling-related degree programs. Although there are studies that examined counseling HIV/AIDS knowledge, the instruments that were used were limited in ways that may compromise the accuracy of the inferences that were made. This study was carried out in three phases. Phase 1 involved developing an initial pool of items; Phase 2 involved an expert review for content validation as well as a pilot-test; Phase 3 involved field testing the CHAKA. The field-test involved 343 undergraduate and graduate students at Southern Illinois University. Item response theory (IRT) was used to analyze the data. Before the data were analyzed, they were examined to see if the CHAKA was a unidimensional test. Results of the factor analysis performed was that the CHAKA may not be unidimensional; however the internal consistency was decent (a = 0.734). A two-parameter logistic (2PL) model was fit to the data. Results from the item parameter estimates displayed relatively low discrimination and difficulty parameters in addition to some problematic items (i.e., negative discrimination estimates, unusually large difficulty values). Additional analyses revealed that locally dependent items may have accounted for the possible multidimensionality, low discrimination indices, and inflated difficulty values. The low discrimination values likely affected the information values of the items and the test. All item information values were less than 1. Last, both uniform and non-uniform differential item functioning (DIF) was present between undergraduate and graduate students. IRT appears to be a promising approach to instrument development in counseling-related programs. Although the CHAKA properties were not ideal, further revisions and a larger sample size may contribute to the overall improvement of this instrument. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]