Over the past five years, Massachusetts has experienced a surge in age restricted "active adult communities" - developments limited to residents 55 years of age or older, according to this new study. CHAPA commissioned this study to better understand how much of the 55 and over market is demand driven; how much is industry initiated; whether local land use regulations and fiscal considerations have contributed to its explosive growth; and at what cost, if any, the growth in age restricted housing has come. The study finds that more than 24,000 units of age-restricted developments have been built, are under construction or in the planning stages. Very few such developments existed in the state prior to 2000.