OBJECTIVE: This project used mixed methods to expand the understanding of social ecological constructs important to youth and develop measures to assess these constructs. METHODS: Eight focus groups and 24 cognitive interviews were conducted with adolescents and caregivers. These were followed by a survey completed by 440 youth ages 10-21 (average age: 16.38, standard deviation[SD] = 3.04). RESULTS: Qualitative data revealed social ecological constructs that have received little prior research attention. These include three psychosocial strengths: relational motivation (inspiration from key adults), group connectedness (bonded to others in teams or organizations), and mattering (knowing your importance to significant others). One outcome was also identified: family well-being (subjective psychological functioning of the family). Psychometric analyses indicated that the new quantitative measures have good to excellent reliability and validity. IMPLICATIONS: The social ecology is complex and extends beyond commonly studied constructs such as social support and collective efficacy. More comprehensive assessments can further research.