This article calls for research on the expertise of youth development practitioners. We argue for studies focused on understanding youth practice from practitioners' points of view--as they experience and enact it--with the aim of contributing findings and frameworks that are helpful to their work and learning. To improve youth programs, first, it is essential to better understand the challenges frontline staff face in their work. We review evidence showing that running a program and facilitating youth development is more challenging and multidimensional than is generally appreciated. Second, it is essential to understand the strategies effective practitioners employ to address these challenges. Studies indicate that the expertise of frontline staff is central to program impact; we review findings suggesting the diverse, contextually-attuned skills this expertise entails. Case studies in three domains of decision-making (designing programs, youth's motivation, and ethical dilemmas) are used to provide a vision for this research.