The purpose of this study was to collect outcome data on the measurement of critical thinking skills of entry and exit level master's nursing students to determine if a difference in critical thinking skills existed between the groups. The sample was drawn from a master's nursing program at a small, private, liberal arts college. This study sought to answer several related questions. Does gender, age, race, marital status, or years of nursing experience effect critical thinking skills? Does past nursing education implement critical thinking skills? Does master's nursing education impact favorably upon the development of critical thinking skills? The theoretical framework for this research was provided by Ausubel's Assimilation Theory of Learning. A descriptive comparative design with a two group posttest only was selected for the study. Participants were asked to complete the California Critical Thinking Skills Test and a demographic data survey. Thirty five master's nursing students (entry level n=18, exit level n=17) completed the two data collection tools. Data analysis utilized descriptive statistics for the demographic data, correlational statistics for the multi-item variables, analysis of variance, and the Number Cruncher Statistical System software. This limited study, variables such as gender, age, race, or marital status were not correlated significantly with critical thinking skills as measured by the California Critical Thinking Skills Test. An incidental finding revealed a higher self-reported grade point average of the exit level group than the entry level group (605). The exit level group scored significantly higher than the entry level group on the California Critical Thinking Skills Test and on the subscales of evaluation, inference, and inductive reasoning. The hypothesis that critical thinking skills increase as master's nursing students advance through their master's nursing education was supported. Recommendations for further study include a follow-up of the present entry level sample before graduation, the use of a two group pretest-posttest design at entry and exit of the nursing program, increasing the sample size, and participating in a multisite study with other nursing education programs.