Designing, developing, and implementing a multi-year randomized control trial targeting what works in gifted education mathematics study is challenging, at best. In response to the United States Department of Education's Institute of Education Sciences request for proposal, we carefully constructed a mixed-methods study by assembling a diverse team of experts. We needed a team of scholars who could bring complementary skill sets to the project, specifically expertise in gifted and talented education, quantitative measurement, curriculum development, professional development, and qualitative research. Our overarching goal was to develop rigorous mathematics curricula to challenge all students in academically diverse classrooms. This project progressed through curriculum design, subject recruitment, baseline data collection, professional development, curriculum implementation, post-data collection, data analysis, and dissemination of findings. Each phase presented both unique opportunities and challenges. The opportunities and challenges are shared to provide guidance for current and future researchers. All research is a "work in progress." On paper, sound research designs, appropriate sample sizes, plans for quality interventions, and carefully matched research questions and analysis techniques often signal potential success. The realities of moving from "paper promises" to research in schools are shared in our research methods case of integrating interviews, focus groups, and observations to examine teachers' and administrators' reactions to grade 3 pre-differentiated and enriched mathematics units. [This content is provided in the format of an e-book.]