The purpose of this study was to investigate how clinical mental health counseling practicum students and practicum instructors use per session assessment feedback with clients they served at a university counseling center. Per session assessment and feedback has been shown to increase the treatment outcomes that counselors achieve while treating clients, and has been shown to reduce drop out rates for clients who are underperforming during counseling (Lambert et al., 2001). This study used a mixed methods research design that was predominantly a qualitative multiple case study design. The researcher interviewed clinical mental health counseling practicum students and practicum instructors that had used the per session assessment and feedback program over the course of a semester with clients at a university counseling center. The quantitative analysis of the counseling center clientele showed that clients left counseling with significantly less symptomology then when they appeared, measured by the pre counseling to post counseling Outcome Questionnaire 45 (OQ 45) scores. This finding suggested that clients at the counseling center found the counseling they received by the clinical mental health counseling practicum students to be effective. The qualitative analysis of the interview data collected from the clinical mental health counseling practicum students and practicum instructors revealed the following themes: (a) perception of feedback, which included the sub themes of uncertainty, integration, and clients experience of feedback (b) application and use, which included the subthemes of process of using feedback, treatment planning, and supervision (c) feedback mechanisms, which included the sub themes of visual cue of client performance, red warning flags, critical item status areas, and tracking effectiveness, (d) discrepant feedback, and (e) suggestions for improvement. This study included rich description about how clinical mental health counseling practicum students and practicum instructors incorporated the use of the feedback system, and found that per session assessment and feedback had a beneficial impact on practice. It was discovered that the use of the feedback program impacted treatment planning, and supervision positively, and created a negative feedback loop that appeared to help decrease anxiety and increase counselor self-efficacy in the clinical mental health counseling practicum students. [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.]