Developmental theory has long emphasized a range of skills that young children need for healthy development across the life course. Nevertheless, most evaluations of early childhood programs and policies have focused on measuring a somewhat limited set of competencies. In this article, we explore this "streetlight effect" in early childhood intervention research and propose an initial set of skills that we argue should be prioritized alongside traditionally measured outcomes as targets of intervention during the preschool period (i.e., between ages 3 and 5 years). These skills, which we call the foundations of learning and development (FOLD) skills, include both well-studied and emerging constructs such as curiosity, creativity, self-regulation and executive function, critical thinking, perspective taking, and internal representations of self. To better understand FOLD skills' potential as more practical, effective, and inclusive targets of early childhood programs and policies, we review research regarding each skill's malleability, measurability, predictive validity, and universality. We end with a set of future directions for the field, including the need to (a) formulate a more inclusive taxonomy of FOLD skills that incorporates currently omitted competencies relevant to marginalized populations, (b) measure these skills in scalable and actionable ways, and (c) enhance or modify intervention strategies to optimize the development of these FOLD skills in the preschool period. (PsycInfo Database Record (c) 2025 APA, all rights reserved).