Excessive anxiety among elementary age students is common, severely impairs academic, social, and behavioral functioning, and is associated with significant educational and health care costs. Despite the high burden of anxiety, less than half of children with anxiety receive the services they need to succeed in school. School clinicians can and do support these youth, however, their caseloads are high and their time to provide individualized services is limited. Consequently, there is a critical need to expand the network of providers who can assist students with anxiety and address this malleable obstacle to student academic success. Because somatic complaints, such as headaches and stomach aches, are a hallmark feature of excessive anxiety, school nurses are often the first school-based personnel to identify problematic anxiety in students. However, school nurses currently lack training in evidenced-based anxiety reduction interventions. The current study leverages findings from a three-year IES Development award (R305A140694), through which our team developed and assessed the feasibility of training elementary school nurses to use a brief intervention to reduce student anxiety; it was demonstrated that the training and intervention (i.e., Child Anxiety Learning Modules; CALM) was indeed feasible to implement and resulted in positive changes in student outcomes. CALM is now a fully developed intervention with ready-to-use intervention components and materials, training and coaching procedures, and is ready for an initial efficacy evaluation in authentic school settings. Toward that end, the primary purpose of this study is to evaluate the efficacy of CALM in a fully powered randomized controlled trial. CALM will be delivered by elementary school nurses in rural, suburban, and urban elementary schools nationwide to enhance the generalizability of findings across socioeconomic, racial, ethnic, and neighborhood settings (as approximately 80% of schools in the US have a school nurse). The efficacy of CALM will be tested using gold standard methods (e.g., independent evaluators to assess primary outcomes). The study's primary aim is to evaluate the efficacy of CALM, compared to a credible comparison condition (CALM-R; a school nurse delivered relaxation skills only intervention that parallels CALM in time and format) as well as a waitlist control, for reducing anxiety symptoms and improving educational outcomes at post-intervention and a one year follow-up. The secondary aim is to examine the cost effectiveness of CALM relative to CALM-R and the waitlist control. An exploratory aim is to examine potential predictors, moderators, and mediators of student outcomes based on the proposed theory of change. If efficacious, CALM will be the first evidenced-based school nurse delivered intervention to assist youth with excessive anxiety, filling an important gap in current practices.