Many developmental changes occur across the first year of life, including areas of cognitive, social, emotional, and physical growth. One challenge of developmental research is to understand the complex set of factors that influence behavior within and across these domains of functioning and change. The present research attempts to illuminate the effects that parent relationships and interactions have on infants' ability to explore non-obvious object properties during free play. In our findings, the role of attachment, parents' actions on objects, parental sensitivity during play, and synchronous interaction all related to an increase in infants' object exploration when playing alone versus playing with a parent. These parent relationship and interaction factors affected infants' exploration differently at 6 months than 12 months. Overall, relational factors appeared of greater important for infants' more thorough object exploration than simply parents' actions on objects. The social context was important for the cognitive outcome of infants' object exploration.