Preschool expulsion is a trending social problem. To date, this is the first study that examines the teacher decision factors behind preschool expulsions. This article presents results of the development and validation of the Preschool Expulsion Risk Measure (PERM). In a 2-phase analysis of the study, we provide evidence for the PERM's reliability and validity in a sample of 352 preschoolers from 88 sites in a New England state. The PERM yielded 4 factors (classroom disruption, fear of accountability, hopelessness, and teacher stress) and demonstrated good internal consistency. The PERM correlated with standardized assessments of children's behavior problems and predicted intervention status (target child vs. random peer) and the probability of expulsion (child considered for expulsion vs. child never considered for expulsion). Classroom disruption predicted intervention status whereas accountability predicted consideration for expulsion. Results support the PERM as a viable tool for assessing the propensity to be expelled. Findings shed light into the decision factors that propel teachers to consider expulsion of a child, which can inform early education programs and policies to address this issue.