Studies of parental supervision often fail to consider the broader ecology in which youth are developing. In this paper, moderation and mediation analysis were utilized to examine parental supervision along with the ecological asset of supportive relationships, which have been identified as especially powerful assets, in a sample of 289 adolescents from the United States. These factors are considered in relation to positive indicators that have specifically been associated with youth thriving: self-control and future aspiration. Results of a mediation analysis suggest that family support mediates the relationship between parental supervision and both indicators. Therefore, parents should ensure they are demonstrating support during attempts to supervise youth. In addition, supportive relationships with adults at school further promote the development of an important internal characteristic: self-control. Including aspects of the broader ecology in studies of youth development is essential to uncovering the role external assets play in promoting positive outcomes for adolescents.