Background: The experience of supervising an underperforming student (UPS) in clinical education and failure to fail (FTF) are described in health professions such as nursing and medicine but there is little description of it in Physical Therapist (PT) clinical education. Purpose: To explore the PT clinical instructors' (CIs) perceptions, practices and experience when supervising an under-performing student, and to determine if failure to fail exists in PT clinical education and if so, what organizational, personal, and demographic factors may be related to it. Methods: A non-experimental, descriptive, explanatory sequential mixed methods design, consisting of investigator created electronic survey, followed by semi structured interviews, using a qualitative phenomenological approach was employed. Snowball sampling was used for the survey. Interview participants volunteered at end of survey. The survey asked CIs questions regarding their perceived role, ability, and grading practices. CIs who had supervised an UPS where asked questions specific to their experience. Delphi process for face and content validity, Exploratory Factor Analysis (EFA) for construct validity and Cronbach alpha (alpha=0.721) for survey internal consistency reliability were used. Descriptive statistics and Spearman correlation assessed associations between variables. Interviews were transcribed verbatim. Transcripts were coded using in-vivo and descriptive coding then collapsed into categories for thematic analysis. Interviews were conducted until saturation in codes was achieved. Intercoder consensus was obtained. Results: 397 CIs completed the survey; 177 had supervised an UPS; 7 participated in interviews. EFA showed variables loaded on 8 factors: DCE support, stress/time, perceived ability, doubt-distress, pressure to pass, professional duty, failure to fail (FTF) perceptions, and co-worker support (Eigenvalues >1). Greater than 95% of CIs agreed they would be able to effectively manage an UPS, and they have a duty to both profession and student to provide objective evaluations. Despite this, greater than 50% agreed they would submit a satisfactory evaluation to an UPS who was trying, in an earlier experience or not experiencing safety issues. Of those who had supervised an UPS, > 60% experienced stress, distress, and conflict. Strategies used by CIs included: one-on-one practice/instruction, feedback, goal setting and lowering expectations. 14% reported that they had FTF an UPS. Reasons cited were student effort/improvement or it was an early experience. There were significant, weak, correlation between perceptions of failing (r=0.294, p=0.000), pressure to pass (r=0.174, p=0.030), sense of duty (r=0.-182, p=0.023), support of DCE (r=0.-194, p=0.024), CI perceived preparation and ability (r=-0.170, p0.034) with FTF. Qualitative data revealed that CIs' experience supervising an UPS was difficult and challenging and they experienced negative emotions. CIs had negative perceptions of failing a student. Student level in the program played a role in FTF. Despite a weak correlation, comments reflect support from DCE and coworkers as beneficial (1497). Conclusions: Supervising an UPS is difficult and challenging. FTF does occur in PT clinical education. No conclusions can be made based on statistical correlations due to the low strength of relationships. Qualitative analysis supports that student level in the program and support from academic institution may play a role in FTF. [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.]