Formative experiments offer researchers the opportunity to partner with classroom teachers to design interventions to address problems that occur in the classroom. The teacher identifies goals for the students, and then the teacher-researcher team designs interventions to meet these goals. During the study, the team modifies the intervention as needed to more effectively address the goal. In this case study, we reflect on our experience conducting a yearlong formative experiment with the goal of fostering a love of reading among students in a diverse urban first-grade classroom. The formative approach allowed us to collaborate with a classroom teacher and develop instructional interventions designed and later modified to meet the specific needs of her students. However, formative experiments also pose challenges such as the collection and management of large amounts of qualitative data, issues of power in the research team, and constructing robust arguments in the absence of strict control of variables. In this case study, we reflect on each stage of the formative experiment, comment on the affordances and drawbacks of this approach to early literacy research, and offer advice for researchers considering this method of inquiry.