Several recent studies have identified both the short and long-term consequences of being born low birth weight. But to what extent are the processes that link early childhood conditions to later adult outcomes driven by biological factors or by social ones working within the family? To what extent are parental investments used to compensate or reinforce birth endowment differences among siblings? I use birth weight and time diary data from a sample of 538 siblings from the Panel Study of Income Dynamics-Child Development Supplement to address these questions. The preliminary findings suggest that parents adopt a compensatory investment strategy during early childhood when the impairments associated with being born low birth weight largely center around limitations to physical functioning (e.g. gross and fine motor skills, spatial abilities, etc.). By age 6, when children begin entering school and achievement based differences become either more noticeable or relevant, investment strategies reverse; normal weight children begin to receive increasingly more maternal time than low birth weight children. These findings suggest that the adult disadvantages faced by low birth weight children may not simply be the result of biological destiny but also due to social dynamics within the family that both compensate and reinforce early life disadvantages among children.