In this qualitative study, 4 elementary classroom teachers who implemented a quasi-experimental study of reading fluency described their experiences. Themes that emerged from analysis of interview transcripts indicate that these teachers considered the value of the fluency study (benefit to students, curriculum fit, and feasibility), their personal interest in the topic (gaining new materials, new strategies, and new learning), and efficacy for meeting the requirements of the study (viability of research requirements, comfort with challenges) when choosing to participate and when making implementation decisions. These 4 teachers' interpretations give insight into the tension between constraints of participation in experimental studies and teacher agency, and into the features of research studies that teachers may consider as supportive of involvement. (Contains 1 table.)