California's Statewide Prevention and Early Intervention (PEI) activities funded by the California Mental Health Services Authority (CalMHSA) under Proposition 63 included PEI training in mental health for staff from K-12 schools in California. RAND evaluated a subset of these PEI trainings using an anonymous survey that asked participants to report, before and after the training, their confidence in their ability and likelihood to refer and intervene with students with social-emotional needs. Participants also reported on their general satisfaction with trainings. Participants completed either a retrospective survey (reporting pre- and post-training responses in one sitting) or a pre-post survey (reporting before and after training). Findings provide preliminary evidence that PEI K-12 trainings have been helpful in increasing participant confidence in and ability to intervene and refer, and this finding was consistent across the K-12 grades and across a diverse group of training participants. [This research was conducted in RAND Health, a division of the RAND Corporation. For "Mental Health Trainings in California's Higher Education System Are Associated with Increased Confidence and Likelihood to Intervene with and Refer Students," see ED561198.]