Afterschool programs routinely provide or supplement Computer Science (CS) education to K-12 students in the United States. How- ever, such opportunities are rarely available to students from low- income communities due to limited computing resources and CS instructors. One strategy for increasing access to instructors in such settings is to train afterschool staff to teach CS to students in their programs. To investigate the viability of this approach, we recruited and trained three afterschool staff with little prior computing experience to teach their students block programming. We analyzed data from teaching observations and survey-based teaching reflections to understand high-level challenges to this strategy. We found that instructors internalized students’ successes and failures as reflections of their own CS teaching ability, and they sometimes struggled to adapt the structured teaching materials to the informal nature of afterschool programs. We reflect on the consequences of these insights and suggest strategies to increase access to CS instructors in low-income afterschool settings.