Intentionally linking the assessment of student learning outcomes of service-learning with reflection allows each to inform and reinforce the other. This paper traces the evolution of a strategy that uses reflection products as data sources to assess and improve both individual student learning and program-wide approaches to reflection. Two tools were developed to guide the process of reflective writing in two courses. Associated rubrics were used to evaluate the quality of thinking demonstrated in the written reflection. Results suggest that these tools can improve students' higher order reasoning abilities and critical thinking skills relative to academic enhancement, civic engagement, and personal growth, and as a result, can improve the overall quality of their thinking and learning. However, this assessment has also surfaced the need for further improvement, particularly with respect to academic learning outcomes. (Contains 8 tables.)