I will present a semiclassical framework to determine the scaling dimensions of composite operators in conformal and quantum field theories. As a main example I will focus on the λϕ^4 theory and show how to obtain the full spectrum of composite operators built out of n fields transforming in the traceless-symmetric Lorentz representations to the next-to-leading order in the double-scaling limit n→∞, λ→0 with λn fixed. At any given order the semiclassical expansion resums an infinite number of Feynman diagrams providing a systematic path to predict higher order terms in the traditional perturbative loop expansion.