Alternative approaches to evaluating critical thinking skills are needed, as pencil and paper assessments may not accurately predict simulated or actual clinical performance. To ensure patient safety, it is imperative to determine how to best promote and measure critical thinking skills. Few studies have examined how these skills are related to performance in a simulated or actual clinical setting. The purpose of this study was to examine the relationship between metrics of critical thinking skills and performance in simulated clinical scenarios and identify predictors of simulation-based performance of nursing students in their last term of academic preparation. A convenience sample of 36 student nurses prepared at the diploma (n=14), associate (n=12), and baccalaureate (n=10) level in their last term of academic preparation participated in a measurement of critical thinking skills and simulation-based performance using videotaped vignettes (VTV), high-fidelity human simulation (HFHS), and two standardized tests: the California Critical Thinking Disposition Inventory (CCTDI) and California Critical Thinking Skills Test (CCTST). Simulation-based performance on the VTV and HFHS assessment was rated as "meeting" or "not meeting" overall expectations and in six categories: problem recognition, reports essential data, initiates appropriate nursing interventions, anticipates medical orders, provides rationale, and prioritizes the situation. Student scores on the CCTDI and CCTST were categorized as strong, average, or weak critical thinking disposition or skills. A majority (75.0%) of students did not meet overall performance expectations when assessed using VTV and HFHS. Those not meeting expectations had difficulty recognizing the clinical problem and reporting the appropriate findings to the physician. There was no significant difference between overall performance based on the method of simulation (VTV or HFHS). However, more students met performance expectations for the category of initiating nursing interventions (p=0.0002) using HFHS. The relationships between VTV performance and CCTDI or CCTST scores were not significant except for the relationship between the category of problem recognition and overall CCTST scores (Cramer's V = 0.444, p = 0.029). There was a statistically significant relationship between HFHS performance and overall CCTDI scores (Cramer's V = 0.413, p = 0.047). Gender, educational preparation, internship/residency participation, prior nursing aide experience, and number of classes using HFHS as a teaching method were not related to overall VTV or HFHS performance or scores on the CCTDI or CCTST. However, there was a significant relationship between age and overall CCTST scores (Cramer's V = 0.388, p = 0.029). The CCTDI, CCTST, and level of educational preparation were not statistically significant predictors of VTV performance. Student nurses' performance reflected difficulty meeting expectations when tested in both simulated settings. HFHS appeared to best approximate scores on a standardized metric of critical thinking. Further research is needed to determine if results of simulated performance predicts application of critical thinking skills in a clinical setting. [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.]