The purpose of this study is to test the effectiveness of a universal, digital, single-session intervention for youth mental health, functioning, and well-being, when implemented with Ukrainian children and adolescents. The intervention teaches well-established procedures that research has shown to be effective in helping American children calm themselves and regulate emotions, including slowed breathing and peaceful mental imagery. The intervention has not been tested previously with Ukrainian students. Participants will be provided access to this brief online program as part of the school curriculum. Students will be randomly assigned to receive the digital program either immediately or after 2 months. This 2-month lag will allow for evaluating the effectiveness of Project Calm in improving students' mental health, well-being, and self-calming skills. This will also allow for evaluating the effectiveness of such an intervention for war-exposed youths for whom these interventions may be especially helpful given the gap between these children's needs for mental health services and the very limited availability of clinicians

Russia's invasion of Ukraine has deeply impacted the nation's children, perhaps most strikingly those who remain in Ukraine and are confronted by the trauma of war. 2.5 million have fled their homes, but even those still at home endure explosions, violence, loss of loved ones, and an estimated average of 900 hours hiding in bunkers. Research in Ukraine shows high levels of child mental health (MH) problems, including anxiety, depression, interpersonal stress, and difficulty regulating emotions. PI Weisz works with child MH researchers and clinicians from Ukraine and 5 other countries (the GROW consortium) to plan psychological support for these children. The group has concluded that Ukrainian-language digital MH interventions teaching evidence-based coping skills are the optimum form of early psychological support at this time, given the massive number of war-exposed Ukrainian children, the dearth of professional clinicians, and the ready accessibility of digital devices. Brief digital interventions (BDIs) for MH have been found effective with children in >90 randomized controlled trials (RCTs). They require no professional training or funding, and are easily implemented via digital devices used in nearly all schools. Ukrainian children may be helped via a BDI that teaches them evidence-based procedures for calming themselves when they experience distressing emotions.

The Harvard Lab for Youth Mental Health is collaborating with Ukrainian schools in the Zhytomyr region, which has been repeatedly targeted by Russian missiles since the first month of the invasion, spreading fear throughout the population and destroying airports, residential neighborhoods, hospitals, and at least one school. Children in Zhytomyr experience war-related MH problems identified in Ukrainian research reviews, including anxiety, sadness, and difficulty calming and regulating distressing negative emotions. Students will be offered a BDI that addresses these problems by teaching well-established skills that have robust empirical support: Project Calm teaches children to calm and regulate distressing emotions by using skills such as slowed breathing, relaxing of tense muscles, and peaceful mental imagery. This 30-minute BDI, which has been refined via student and school staff feedback over a 2-year period, is highly rated by children and teens, and has already been accessed >1000 times in North America.

Project Calm will be tested via an RCT with a time-matched, school-related control activity; students will be randomized 50/50 to complete Project Calm after the baseline assessment or after a 2-month lag. Students in grades 4-12 will complete MH, wellbeing, and BDI-skills measures at baseline and 1-, 2-, 3-, and 4-months post-baseline. Data collection will span January - June of 2024. Findings may point the way to a highly scalable, accessible, and disseminable approach to MH support-easily implemented in schools or community settings-that could benefit Ukrainian children and, with translation and adaptation, war-affected children of other nations.

Inclusion Criteria:

• Youth in grades 4+ at partnering schools for Ukrainian children
• Youth and at least one guardian consent to adolescent participation in study
• Youth reads Ukrainian well enough to effectively complete the digital programs
• Youth has access to a digital device

Exclusion Criteria:

• Youth does not have access to a digital device
• Youth has an intellectual disability that precludes comprehension of the program content

Analytic code will be made available upon publication of trial results. Study protocol and statistical plan are available on Open Science Framework.

Assessments will be completed independently by participants online. Investigators will be blinded to condition throughout the study.