There is no shortage of urgent, complex problems that mathematics education can and should engage with. Pandemics, forest fires, pollution, Black Lives Matter protests, and fake news all involve mathematics, are matters of life and death, have a clear political dimension, and are interdisciplinary in nature. They demand a critical approach. The authors in this volume showcase new insights, teaching ideas and new and unique ways of applying critical mathematics education, in areas as diverse as climate change, obesity, decolonisation and ethnomathematics. This book demonstrates that there is plenty to be done with critical mathematics education. Contributors are: Annica Andersson, Tonya Gau Bartell, Richard Barwell, Lisa Lunney Borden, Sunghwan Byun, Anna Chronaki, Brian Greer, Jennifer Hall, Victoria Hand, Kjellrun Hiis Hauge, Beth Herbel-Eisenmann, Rune Herheim, Courtney Koestler, Kate le Roux, Swapna Mukhopadhyay, Aldo Parra, Anita Rampal, Sheena Rughubar-Reddy, Toril Eskeland Rangnes, Ulrika Ryan, Lisa Steffensen, Paola Valero and David Wagner.