This dissertation provides a start-to-finish description of development, administration, and validation for an online middle-school physics test using a DCM framework with response-time. The first paper illustrated the process of implementing DCM with a careful selection of the content domain and a simulation approach for a Q-matrix construction. The results were promising despite some items that showed inadequate fit and quality. The second paper is a narration of a step-by-step validation process for the effects of the DCM-scored physics assessment on learning and teaching. While evidence was found to support multiple validity arguments and the usefulness of the diagnostic feedback, validity threats were also found because one of the students identified multiple strategies in solving some of the questions. The third paper investigates the potential benefits of incorporating response-time into the diagnostic model. Although the response-time variable did not improve the classification estimation in this case, different types of relations between the ability, time variable, or other ancillary variables should be investigated in the future. Although limitations were found in the dissertation, multiple actions could be taken to refine this process in future research, and the process could still be generalized into other domains and as guidelines for researchers and educators interested in DCM application. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]