The prodigious writings of Martin Gardner, from his Mathematical Games column in Scientific American to the 70-plus books he authored, had an enormous influence on the field of recreational mathematics. This book collects articles Gardner wrote for the MAA in the twenty-first century, together with other articles the MAA published from 1999 to 2012 that are inspired by his work. Eight of Gardner's articles are presented here: together they represent his playful and engaging approach to recreational mathematics, and the breadth of his interests, spanning geometry, number theory, graph theory, probability, and pseudo-science. The remaining 33 chapters are a diverse collection of responses to Gardner's work, many of which address open problems. This book is a tribute to the deep and lasting impact of a prolific and brilliant writer. It is for anyone who, like Martin Gardner, loves mathematics.