The dataset contains infant freezing observations at 15-months of age, as well as raw data of self-reported internalizing symptoms (ages 9, 12, 14, and 17), parent-reported internalizing symptoms (ages 5, 9, 12, 14, and 17), parent-reported externalizing symptoms, quality of parental behavior, social peer preference, other temperamental fearfulness assessments and genetic data on 5-HTTLPR. This data was used for analyses in the research described in the Developmental Science paper by Niermann et al. (2018). The current study tested prospectively whether observed freezing in infancy predicted the development of internalizing symptoms from childhood through late adolescence. A full description of the procedure and the measures is given in the Methodology file. The R-syntax files contain a description of data as well as all steps of data analysis that were performed. The results of these analyses are described in the paper.