Research suggests that school reform initiatives have had minimal success in engendering systemic instructional improvement in schools. Within this evaluative context, this paper explores the means through which the paradigm of thinking about school instruction dominant in the profession (that is, Hirsch's "thoughtworld") potentially affects the actions of school-based personnel addressing instructional problems in school reform. The paper examines the implications of a year-long project for school-based reform that successfully improved remedial students' academic reading and affective performance in grades 3 and 4. The study follows the evolution of teachers' perspectives from one of initial concerns regarding the efficacy of a nonparadigmatic direct-instruction reading program, to strong advocacy for its expected student outcomes and the desirability of its design characteristics. The text interprets the teachers' prior instructional expectations and perspectives as barriers to change that reflected a dominant paradigmatic perspective. Accordingly, the paper offers a framework for incorporating consideration of research-based informational dynamics into the processes of school-based reform environments. Finally, the paper offers policy recommendations based upon the analysis presented that promise to enhance the effectiveness of school-based instructional improvement. (Contains 30 references.) (RJM)