Six remedial reading teachers in a large, rural school district participated in a form of professional development called Teaching as Intentional Learning, based on an inquiry process. Their topic of inquiry was formative assessment. Professional development comprised both direct instruction and inquiry learning in teachers' own classrooms. This study describes the strategies they experimented with, their professional growth in formative assessment, and effects on students. All six teachers showed important professional growth, as indicated by their own reflections and also by their supervisor's observations. In First Grade, at-risk students assigned to these project teachers had increased reading readiness scores on one measure (DIBELS PSF) compared with at-risk students assigned to non-project teachers. (Contains 2 tables, 1 figure and 1 note.)