Let F be a class of functions on a probability space (Ω, µ) and let X 1 , ..., X k be independent random variables distributed according to µ. We establish high probability tail estimates of the form sup f ∈F |{i : |f (X i )| ≥ t} using a natural parameter associated with F . We use this result to analyze weakly bounded empirical processes indexed by F and processes of the formWe also present some geometric applications of this approach, based on properties of the random operatorare sampled according to an isotropic, log-concave measure on R n .