The **aim** of this project is to investigate whether observational learning has developmental significance for early helping behavior in the second year of life. Thereby, it will substantiate recent theoretical assumptions (and initial studies) on the role of social experiences in the emergence and development of early prosocial behavior. In **two studies**, this project examines whether prosocial modeling (1) is causally effective, (2) is relevant in infants’ everyday life, i.e., whether it occurs in an infant’s environment in meaningful ways, and (3) correlates with infants’ helping at home (and in the lab) – both contemporaneously and longitudinally. This complementary proof is necessary, since findings on the causal effectiveness of prosocial modeling alone do not necessarily reveal anything about its developmental relevance. For example, if prosocial modeling proves to be effective in the laboratory but children have no (or few) observational possibilities in everyday life, then it is probably not relevant to their prosocial development. Beyond proving that prosocial modeling exists at home, we also perform a longitudinal investigation of correlations between prosocial modeling at home and infants’ helping during the second year of life – using a cross-lagged panel approach – to determine whether naturally occurring modeling impacts children’s prosocial development; this will prove that prosocial modeling is effective outside of laboratory contexts. In **summary**, this project takes a complementary multi-method approach, namely an experimental study to verify the causal efficacy of prosocial modeling (**Study 1**) and a naturalistic study (a) to monitor how often children have opportunities to observe prosocial models in daily life and (b) to explain inter-individual differences in infants’ prosocial behavior based on differences in how often they observe prosocial models outside of laboratory contexts (**Study 2**). This multi-methodological approach is also in line with the recent recommendations for good developmental psychological research. This project is funded by a research grant of the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - project number [454245029][1]. [1]: https://gepris.dfg.de/gepris/projekt/454245029