Vocabulary skills are important for overall reading competence, but vocabulary assessment approaches that inform instructional decision-making and are sensitive to improvement are limited. This article describes a process for developing vocabulary measures designed to facilitate data-driven decision-making for kindergarten and first-grade students who are at risk in vocabulary. A pilot study suggested the measures could be administered and scored with fidelity, and also produced promising data for indices of reliability, criterion-related validity, and sensitivity to growth, particularly for a rating-based scoring metric. Implications and considerations for developing instructionally relevant vocabulary measures are discussed.