We investigate polaron shape and size using electron–phonon correlation functions measured in 1D polaron ground states of the Holstein Hamiltonian. We use the Global–Local variational method as our primary quantitative tool, calling upon weak- and strong-coupling perturbation theories to assist in the interpretation of our results. The spatial extent of correlations is used to quantify polaron size, and is analyzed over a wide range of parameters. Distinct scaling behaviors are found below the self-trapping transition and above it, leading naturally to the notion of the polaron size as an order parameter for a self-trapping transition that becomes critical in the adiabatic limit. The archetypical structure characterizing polaron shape and size below the self-trapping transition is found to differ significantly from what might be expected from certain widely held views.