An attempt was made to develop an objective instrument to assess a teacher's perceived engagement in reflective practice. A Reflective Teaching Instrument (RTI) was developed around three dimensions of reflective practice in teaching: (1) diagnosis (problem setting); (2) testing; and (3) personal causation. Indicators of each of the dimensions were compiled from a review of the literature to generate an instrument. Four educators comprised an expert panel that assessed the face validity of each item. The pilot instrument of 48 Likert-format items was administered to 40 practicing teachers enrolled in graduate classes. A field test was subsequently conducted with 102 public elementary and junior high school teachers, representing a response rate of 94%. Items empirically supported through factor analysis after the field test were retained, resulting in a revised 15-item scale. Reliability coefficients of the revised scale indicated that items appeared to measure the identified constructs. Further research should include refinement of the instrument with attention to the diagnosis subscale, which was of somewhat suspect construct validity. Research to support the relationship between scores on this instrument and teacher effectiveness is also needed. Factor structure and alpha reliability data of the RTI are tabulated. (SLD)