With the online assessment becoming mainstream and the recording of response times becoming straightforward, the importance of response times as a measure of psychological constructs has been recognized and the literature of modeling times has been growing during the last few decades. Previous studies have tried to formulate models and theories to explain the construct underlying response times, the relationship between response times and response accuracy, and to understand examinees' behaviors. Different from most existing psychometric models, the current study is based on the idea of reading comprehension fluency in the reading literature and proposes several item response theory based models combining response times and response accuracy. To better understand the construct of reading comprehension fluency, the current study used a new computer-administered assessment of reading comprehension and recorded both the responses and response times of each item. Response times connect examinees' performance on the reading comprehension test to the concepts of fluency or automaticity in the reading literature, concepts that are evidenced by responses that are accurate and appropriately fast. The current study evaluates reading comprehension fluency through two approaches: one with polytomously scored variables and one with conditional variables. The models show the benefits of using the response time information in terms of improving the construct validity when the measured latent construct is reading comprehension fluency. The current study contributes to an interpretation of the latent trait of reading fluency. The models can be used to identify the intervals along the comprehension continuum in which the students tend to read fluently. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]