Scaling from the traits of individual trees to the properties of forest stands has long been a challenge. I present the Perfect Plasticity Approximation (PPA), which rigorously provides such a scaling based on the vital rates (growth, mortality, fecundity) of trees both in the understory and canopy stages. I discuss how we can apply ecophysiological sub-models to link these vital rates to plant traits, to competition, and to the availability of resources such as nitrogen, light, water, and CO2. A game-theoretic analysis of the integrated model makes predictions of the competitive dominant physiology and allocation strategies of trees across gradients of resource availability and under elevated atmospheric CO2. I compare model predictions with data, where available, and suggest ways that a PPA-based modeling framework can help organize empirical efforts in the age of “big data.”