There are many approaches used to deliver social and emotional learning (SEL) in schools. These include both explicit skills-based curricula and more micro strategies, such as behavioral modeling by teachers, incorporating concepts into academic lessons, and creating opportunities for students to apply skills throughout the school day. However, in most SEL studies, implementation "dosage" is measured only as the number of lessons delivered from a curriculum, failing to account for the various approaches to SEL delivery. Currently, there is a lack of measurement approaches that capture SEL implementation dosage across diverse "dose forms." To fill this gap, this study proposes a measure of "Multiform Dosage," which captures four different dose forms: delivering lessons, modeling, incorporating, and applying intervention concepts. We tested a measurement model of Multiform Dosage with data collected during the implementation of TOOLBOX, a school-based SEL program. Multiple forms of implementation dosage were measured through self-report surveys of K-5 classroom teachers (n = 94) in October, December, and May. The four-factor measurement model with one cross-loading showed a good fit to the data with acceptable loadings at each occasion. Measurement weights were equivalent between K-2 and 3-5 grade subgroups except one loading of the Incorporation factor in October. Implications of these findings are discussed.