Composites are the material of choice today for most of the dental restorative procedure. However, many practioners complin of lesser longivity of the materials or increase chances of sensitivity of teeth when they use composites. The real reason is failure to understand the affects of polymerization shrinkage of the composites. It is the most common cause of the most of the day to day problems associated with dental composites. That was the reason I thought of writing this book. I have tried to include the basic composition of the composites, and in detail about the polymerization shrinkage. How the shrinkage happens, factors influencing it, methods to measure shrinkage, the ways to combat it and the recent developments to reduce it. I hope you will find it an interesting read.