We describe real-space imaging measurements of the interactions and elastic properties of charge-stabilized colloidal crystals. Interactions between charge-stabilized latex spheres self-assembled into colloidal crystals are extracted from single-particle dynamics using new techniques in digital video microscopy. The spheres＇ cooperative behavior makes possible simultaneous measurements of their crystals＇ bulk moduli. Together, these measurements offer new insights into the microscopic origins of charge-stabilized colloidal crystals＇ bulk elastic properties. In particular, they demonstrate that the crystals＇ elastic properties cannot be ascribed to the linear superposition of pairwise interactions. This result highlights the potential pitfalls of using the conventional Derjaguin, Verwey, Landau, and Overbeek (DLVO) theory to describe the bulk properties of charge-stabilized colloidal suspensions.