The Field Instructor Supervision Scale (FISS) measures field instructor supervision behaviors and can be completed by undergraduate and graduate students in diverse practicum settings. The FISS was validated over 4 years with 684 undergraduate and graduate social work students. The final FISS included 18-items and had two subscales: task support and developmental support. Construct validity was established through exploratory factor analysis; Cronbach's alpha was excellent. The FISS was associated with students' self-reported satisfaction, instructor effectiveness, preparedness for practice, learning, and self-efficacy, providing evidence for criterion-related validity. The FISS can be used by field education programs to evaluate students' perception of field instructors' task and developmental support and by researchers to examine the relation between support and student outcomes.