Despite numerous advances in composite resin technology over the course of many decades, shrinkage behavior and the resultant stresses inherent to direct placed composite restorations continue to challenge clinicians. This overview of composite resins includes a review of their history and development along with a discussion of strategies for reducing polymerization shrinkage. An assessment of the clinical significance of these materials is also provided, including a discussion of the differences between polymerization shrinkage and stress, incremental layering versus bulk placement, and the emergence of lower shrinkage stress monomer chemistry.