The Total Testing Process (TTP) refers to the sequence of 11 steps of laboratory testing, beginning with a clinical question prompted by the patient-clinician encounter and concluding with the impact of the test result on patient care. TTP when applied to therapeutic drug monitoring (TDM) emphasizes that TDM must be considered a process involving a series of steps and interrelated activities and not viewed simply as a numerical value for a serum drug concentration. TTP is also an ideal format for organizing and identifying the system-related and patient-centered variables used in outcomes assessment of TDM, as well as providing a template for collecting the cost data needed for economic analyses. Examples are provided for improving application of TDM by practitioners, clinical laboratories, and educators.