Measures implemented to contain the Covid 19 pandemic have led to systematic changes in familiar structures over the past 3 years, resulting in multiple psychosocial stresses among families. Psychosocial stress can have a harmful impact on children's health and development (1-3), with young children being particularly vulnerable (4). Psychosocial stress during the pandemic is reflected in an increase of parenting stress (5-7) and psychological problems among parents (8,9). Given the close association between parenting stress, parental mental health, and parenting behaviors (10-12), it is not surprising that parent-child relationships have also suffered in the course of the pandemic (13). In addition, children may have missed important educational and learning opportunities due to limited access to childcare facilities. These factors might have had an impact on children’s mental health during the pandemic. The Bavaria-wide CoronabaBY study - the first project in Germany to explicitly address psychosocial stress in families with infants and young children during the pandemic – has demonstrated clear signs of psychosocial stress in young families compared to pre-pandemic data (14). Even during periods of low incidences and associated "relaxations" (i.e., the summer months), stress parameters did not decrease. Rather, the number of psychosocially stressed families increased steadily during the course of the pandemic (15). Alongside the pandemic, other societal challenges, such as the onset of the economic crisis, the impact of the Ukraine war, and climate change have led to the experience of “multi-crisis times”, and can fuel fears and concerns about the future and place additional stress on young families. Systematic and reliable identification of families with psychosocial support needs is urgently indicated in order to prevent negative direct and indirect effects on child health. Burdened families could also find easier access to appropriate support services by communicating information in a needs-based manner (e.g., via smartphone app). Hence, we aim to examine (1) psychosocial stress factors in N = 5,000 families with children aged 0-6 years old (2) the effectiveness of an app-based information module on psychosocial support for young families (=intervention). We therefore perform a Bavaria-wide intervention study (JuFaBY) over a study period of 18 months in total with two measurement time points for each participant (at study entry and 6 months later). (1) Werner, E. E. (1993). Risk, resilience, and recovery: Perspectives from the Kauai Longitudinal Study. Development and Psychopathology, 5, 503-515. (2) Laucht, M., Esser, G. & Schmid, M. H. (1997). Developmental Outcome of Infants Born with Biological and Psychosocial Risks. Journal of Child Psychology and Psychiatry, 38(7), 843-854. (3) Laucht, M., Schmidt, M. H. & Esser, G. (2002). Motorische, kognitive und sozial-emotionale Entwicklung von 11-Jährigen mit frühkindlichen Risikobelastungen: späte Folgen. Zeitschrift für Kinder- und Jugendpsychiatrie, 30(1), 5-19. (4) Schlack, H. G. (2009). Sozialpädiatrie: Eine Standortbestimmung. In H. G. Schlack, R. von Kries & U. Thyen (Eds.), Sozialpädiatrie. Gesundheitswissenschaft und pädiatrischer Alltag (pp. 1-8). Berlin, Heidelberg: Springer. (5) Giannotti, M., Mazzoni, N., Bentenuto, A., Venuti, P. & de Falco, S (2021). Family adjustment to COVID-19 lockdown in Italy: Parental stress, coparenting, and child externalizing behavior. Fam Process, 1-19. (6) Spinelli, M., Lionetti, F., Setti, A. & Fasolo, M (2020). Parenting Stress During the COVID-19 Outbreak: Socioeconomic and Environmental Risk Factors and Implications for Children Emotion Regulation. Fam Process, 60(2):639-53. (7) Taubman-Ben-Ari, O., Ben-Yaakov, O. & Chasson, M (2021). Parenting stress among new parents before and during the COVID-19 pandemic. Child Abuse Negl, 117:105080. (8) Panda, P.K., Gupta, J., Chowdhury, S.R., Kumar, R., Meena, A.K., Madaan, P. et al. (2021). Psychological and Behavioral Impact of Lockdown and Quarantine Measures for COVID-19 Pandemic on Children, Adolescents and Caregivers: A Systematic Review and Meta-Analysis. J Trop Pediatr, 67(1). (9) Racine, N., Hetherington, E., McArthur, B.A., McDonald, S., Edwards, S., Tough, S. et al. (2021). Maternal depressive and anxiety symptoms before and during the COVID-19 pandemic in Canada: a longitudinal analysis. The Lancet Psychiatry, 8(5):405-15. (10) Farmer, A.Y. & Lee, S.K. (2011). The Effects of Parenting Stress, Perceived Mastery, and Maternal Depression on Parent-Child Interaction. Journal of Social Service Research, 37(5):516-25. (11) Thomason, E., Volling, B.L., Flynn, H.A., McDonough, S.C., Marcus, S.M., Lopez, J.F. & Vazquez, D.M (2014). Parenting stress and depressive symptoms in postpartum mothers: bidirectional or unidirectional effects? Infant Behavior and Development, 37(3): 406-415. (12) Vismara, L., Rollè, L., Agostini, F., Sechi, C., Fenaroli, V., Molgora S. et al. (2016). Perinatal Parenting Stress, Anxiety, and Depression Outcomes in First-Time Mothers and Fathers: A 3- to 6-Months Postpartum Follow-Up Study. Front Psychol, 7. (13) Russell, B.S., Hutchison, M., Tambling, R., Tomkunas, A.J. & Horton, A.L. (2020). Initial Challenges of Caregiving During COVID-19: Caregiver Burden, Mental Health, and the Parent-Child Relationship. Child Psychiatry Hum Dev, 51(5):671-82. (14) Buechel, C., Nehring, I., Seifert, C., Eber, S., Behrends, U., Mall, V., Friedmann, A. (2022). A cross-sectional investigation of psychosocial stress factors in German families with children aged 0-3 years during the COVID-19 pandemic: initial results of the CoronabaBY study. Child and Adolescent Psychiatry and Mental Health, 16, 37. (15) Buechel, C., Nehring, I., Seifert, C., Eber, S., Laub, O., Ewald, D., Behrends, U., Mall, V., Friedmann, A. (2022). Abnahme der Pandemiebeschränkungen = Abnahme der psychosozialen Belastungen bei Familien mit Kindern im Alter von 0-3 Jahren? Ein repetitiver Querschnitts-Vergleich in Bayern (CoronabaBY-Studie). Posterpräsentation. Kongress für Kinder- und Jugendmedizin 2022. Düsseldorf, 08.09.22.