The introduction of posterior composite resin materials in the 1980’s created a set of restorative problems unique to these new restorations. Placement of posterior composites is technically more challenging than working with amalgam and can result in open contacts, open margins, and incorrectly contoured restorations. Many of these problems were not due to operator error, but to the materials themselves and the way matrix containment systems worked with them. Over the last 25 years, new matrix systems have been developed specifically for posterior composites that address the problems found with the original amalgam matrix systems. This course reviews the history of matrix systems designed for posterior composite restorations and illustrates how they have changed in order to make the optimal placement of these restorations predictable.