In response to the ACTFL's Research Priorities Initiative, the present study used a multiple case study design to examine teacher candidates' ability to implement two high-leverage teaching practices: increasing interaction and target language comprehensibility and questioning to build and assess student understanding. Candidates implemented these practices in K-12 foreign language classrooms following a practice-based methodology course. Findings revealed that candidates could more easily translate some aspects of practice to the field site than others. Generally, teacher candidates scored better on aspects of practice for which they were able to plan and practice than on those that required them to vary from their lesson plans or make in-the-moment decisions. Teacher candidates struggled the most with aspects of practice that involved sustaining meaningful interaction with students.