Over time, all Veterinary Technicians develop their own “toolbox” of essential skills and tools that they consider must-haves in order to effectively and efficiently perform their job. These “toolboxes” may look unique to the individual depending on the years of experience and the specialty wherein they work. Kirby’s Rule of 20 is a well-known critical care nursing tool that helps to aid in the thorough monitoring of a critically ill patient. While this list was originally designed for critically ill patients, it can be used for patients in all areas of small animal medicine. In this lecture, we will review the 20 parameters listed in Kirby’s Rule of 20 and determine how closely monitoring them can help every Veterinary Technician proactively care for their patients. In doing so, we will learn how this tool could potentially reduce or even prevent serious complications in all hospitalized patients regardless of specialty.