The importance of afterschool hours for youth development is widely acknowledged, and afterschool settings have recently received increasing attention as an important venue for youth interventions, bringing a growing need for reliable and valid measures of afterschool quality. This study examined the extent to which the two observational tools, that is, Caregiver Interaction Scales (CIS) and Promising Practices Rating Scales (PPRS), could serve as reliable and valid tools for assessing the various dimensions of afterschool setting quality. The observation data of 44 afterschool programs were analyzed using both standard psychometric procedures (i.e., internal consistency, interrater reliability, and factor analysis) and generalizability theory. The results show the potential promise of the instruments, on one hand, and suggest future directions for improvement of measurement design and development of the field, on the other hand. In particular, our findings suggest the importance of addressing the effect of day-to-day fluctuations in observed afterschool quality.