TY - JOUR AB - Questions about the stability of psychological constructs, skill generalization, and transfer have long motivated psychological research. Despite a proliferation of theory, the field has rarely established causal effects. We employed a novel approach to test the stability and codevelopment of cognitive and social-emotional skills in early childhood using longitudinal randomized controlled trial data from the nationally representative Head Start Impact Study (n = 4,667). Capitalizing on the study’s clustered design, we computed treatment effects on both skills for each cluster (k = 84). Using meta-analytic techniques, we found that changes to children’s cognitive skills persisted at a rate of approximately 40% one year after program end and 30% two years after program end. Changes to social-emotional skills persisted at a rate of approximately 20% at both timepoints, though estimates were statistically non-significant. We observed more consistent, but not statistically significant, support for cognitive to socialemotional skill transfer. While models relying on exogenous variation attenuated traditional correlational estimates of same-skill associations, correlational estimates of cross-skill associations appeared to be less biased. AU - Watts, Tyler W. AU - Botvin, Caroline M. AU - Bailey, Drew H. AU - Hart, Emma R. PY - 2026 ST - Using experimental variation to examine the (co-)development of cognitive and social-emotional skills in early childhood TI - Using experimental variation to examine the (co-)development of cognitive and social-emotional skills in early childhood UR - http://www.edworkingpapers.com/ai26-1369 ER -