In 1997 Longman published his second book "The Return of Thrift: How the Collapse of the Middle Class Welfare State will Reawaken Values in America", which argued that people today are spending in an unsustainable manner with the accelerating decline in fertility rates threatening the financial collapse of the welfare state throughout the world. By 2000 he had linked with the New America Foundation and began work on his most widely read work, "The Empty Cradle" in March 2004. This book expressed his strongly held opinion that sub-replacement fertility and resultant population decline is likely to have catastrophic economic consequences for those nations suffering from it and is also likely to reduce societies' ability to adjust to newly emerging problems because of unwillingness to innovate or take risks. It also examines the present effect of the rapid fall in birth rates around the globe.