This book is intended to be an accessible and useful reference for conducting experimental research into self-propelled micro- and nanoparticles, commonly referred to as "active colloids." These particles show numerous interesting behaviors and have a wide variety of potential applications in energy, environmental remediation, and biomedicine; however, working with active colloids can be daunting. Active colloids are an inherently interdisciplinary field of research, and thus the skills and knowledge needed to succeed in this field span a variety of subjects. This book fills an unmet need for an accessible, practical guide to running basic experiments with active colloids. Early chapters guide the reader through the fabrication of basic active colloid designs, while the middle chapters provide instructional guides on microfluidic assays, microscopy methods, and video analysis. The book also includes a chapter that takes a critical look at the most promising practical applications of active colloids, and what technical advances are needed to realize this promise.