Achievement estimates are often based on either number correct scores or IRT-based ability parameters. Van der Linden (2007) and other researchers (e.g., Fox, Klein Entink, & van der Linden, 2007; Ranger, 2013) have developed psychometric models that allow for joint estimation of speed and item parameters using both response times and response data. This paper presents an application of this type of approach to a battery of 4 types of fluid reasoning measures, administered to a large sample of a highly educated examinees. We investigate the extent to which incorporation of response times in ability estimates can be used to inform the potential development of shorter test forms. In addition to exploratory analyses and response time data visualizations, we specifically consider the increase in precision of ability estimates given the addition of response time data relative to use of item responses alone. Our findings indicate that there may be instances where test forms can be substantially shortened without any reduction in score reliability, when response time information is incorporated into the item response model.