Arnold and Gagnon’s timely work on the 4-H Thriving Model is an excellent example of the application of developmental science in youth development practice. In their article, the authors describe how 4-H, an established youth development organization, updated the theory of change. Designing an actionable theory of change based on science is indeed a commendable effort for any youth-serving organization. However, the work does not stop there. The diverse 4-H system now has the ultimate challenge of adopting and implementing the principles presented in their theory of change. In this commentary, I discuss the often-overlooked components of implementation readiness: motivation, general capacity, and content-specific knowledge (R=MC2) in relation to the 4-H Thriving Model. When staff are ready, they can succeed in aligning resources and coordinate professional learning for the adults, or implementers, to know and understand the theory of change and associated practices. Fostering learning and development to enact science-informed strategies, as Arnold and Gagnon have done in the 4-H Thriving Model, is critical to developing sound models of youth programming. However, to implement a model into practice, the real and human factors of implementation readiness are key to success.