Free radicals, molecules with unpaired electrons, are highly reactive and play key roles in physiologic regulation and in many degenerative and pathologic processes, making them a fertile area of research. This book focuses on spin trapping, a sophisticated technique for the identification of free radicals in biological systems. The method is complex, and this book offers an in-depth guide to all of the critical aspects needed for its application to free radicals in biology. This includes advice on interpreting results, trouble-shooting, and experimental designs. The book looks at future directions in the field and will prove an invaluable resource for investigators working in the biology of free radicals, regardless of whether they are new or highly experienced in the applications of spin trapping.