Purpose. Clinical education is a critical component of the education of physical therapists (PT). Clinical instructors (CIs) are primarily responsible for coordinating and supervising this clinical learning. However, little has been published about how CIs make decisions and solve problems related to clinical teaching and how this instructional reasoning changes with experience with clinical teaching. Therefore, the purpose of this study was to explore the instructional reasoning of novice and experienced CIs. Methods. A qualitative multiple case-study design was used. Data were collected through in-depth interviews and review of clinical teaching artifacts. A coding framework was developed for coding each individual case. Cross-case analysis to examine the impact of experience on clinical teaching was performed. Trustworthiness was established through peer review of data. Credibility was established through triangulation of the data and member checks. Participants. A sample of convenience of PTs who were credentialed as CIs in Indiana was used. Six participants with a range of experience as CIs and clinicians were selected and consented to participate. Results. Four major themes emerged to describe the instructional reasoning of CIs. These themes were communicating expectations for the student's role in the learning process, creating an environment conducive to learning, facilitating student achievement of learning goals, and balancing dual roles and responsibilities. The more experienced CIs clarified expectations for students to be active participants in a challenging learning environment and used well-defined teaching strategies to facilitate student achievement of learning goals that were integrated into the patient care responsibilities. The novice CIs were less likely to clarify expectations and to connect learning goals with teaching strategies. They focused on creating a comfortable environment for learning and were challenged by balancing the dual roles of clinical teacher with responsibilities for patient care. Conclusions. This study provided an in-depth description of the instructional reasoning of CIs and how this instructional reasoning changes with experience. The results indicated that instructional reasoning matures with clinical teaching experience. Clinical education faculty should consider developing strategies to support the development of novice CIs. Strategies to supplement development of student clinical reasoning should also be considered.