As youth navigate their lives, numerous people are uniquely positioned to recognize their struggles. Assessments usually originate from someone becoming concerned and taking action. Referrals may come from many diverse ‘stakeholders’ in the youth’s social ecology, including family and friends, a healthcare clinic, school, legal system, or mental health office, but may also stem from an adolescent themselves. These referral sources are considerably more familiar with the youth than the assessing clinician; as such, they play a key role in the youth obtaining appropriate services. Strategic collaboration with referral sources is critical, as their questions not only shape the goals of the assessment, but also provide critical insights into the youth’s case, support the youth’s engagement, and ultimately impact the ways the resultant recommendations are addressed and implemented. This chapter focuses on approaches for effectively collaborating with referral sources. Through illustrative cases, we demonstrate how clinicians appreciate the unique positionality of stakeholders and their roles in the assessment process. Sample adaptable scripts and questions for stakeholders according to their expertise and role in the child’s life provide a starting point for making the most of these interactions.