In the current climate of accountability and research-based practices in reading instruction, professional development is often identified as one of the key elements needed to change the trajectory of progress for struggling readers and to ensure their ongoing success. Research on teacher quality and its impact on student achievement seems to suggest that teacher quality has a significant effect on student academic achievement. Although enhancing teachers' effectiveness has been the subject of much interest and fascinating speculation, there has been little empirical research to document the factors that make professional development optimally effective. The purpose of this article is to propose a conceptual framework of factors that support professional development and sustain its impact on reading improvement. In addition, I suggest several important questions that could be answered if a science of professional development is realized.Successfully teaching children to read is one of the most important functions of schools. Despite increased interest, expanded fiscal allocations by local, state, and federal education agencies, and heightened political attention, reading outcomes for many children remain disappointingly inadequate (National Center for Educational Statistics, 2000). One explanation for low reading outcomes stems from the inability of schools and teachers to meet the needs of struggling readers, many of whom will eventually be identified as requiring special education. Despite important intended outcomes of specialized remedial reading programs for struggling readers, very often students who are demonstrating difficulties in reading in the primary grades do not improve (Juel, 1988;Torgesen et al., 1999).In the current climate of accountability and research-based practices in reading instruction, professional development is often identified as one of the key elements needed to change the trajectory of progress for struggling readers and to ensure their ongoing success. Moreover, research on teacher quality and its impact on student achievement EXCEPTIONALITY, 12(3),[175][176][177][178][179][180][181][182][183][184][185][186][187][188][189][190][191]