Jet substructure observables, designed to identify specific features withinjets, play an essential role at the Large Hadron Collider (LHC), both forsearching for signals beyond the Standard Model and for testing QCD in extremephase space regions. In this paper, we systematically study the structure ofinfrared and collinear safe substructure observables, defining a generalizationof the energy correlation functions to probe $n$-particle correlations within ajet. These generalized correlators provide a flexible basis for constructingnew substructure observables optimized for specific purposes. Focusing on threemajor targets of the jet substructure community---boosted top tagging, boosted$W/Z/H$ tagging, and quark/gluon discrimination---we use power-countingtechniques to identify three new series of powerful discriminants: $M_i$,$N_i$, and $U_i$. The $M_i$ series is designed for use on groomed jets,providing a novel example of observables with improved discrimination powerafter the removal of soft radiation. The $N_i$ series behave parametricallylike the $N$-subjettiness ratio observables, but are defined without respect tosubjet axes, exhibiting improved behavior in the unresolved limit. Finally, the$U_i$ series improves quark/gluon discrimination by using higher-pointcorrelators to simultaneously probe multiple emissions within a jet. Takentogether, these observables broaden the scope for jet substructure studies atthe LHC.