Cardiac resynchronization therapy (CRT) has been shown to improve cardiac function, diminish hospitalization frequency, and enhance quality of life in selected heart failure patients. This benefit is mostly due to improved synchronization of ventricular contraction in the diseased heart. Since heart failure patients represent a heterogeneous group, cardiac resynchronization therapy must be tailored to each patient. Thus the best performance can be achieved by optimal programming of the device for each individual. This communication discusses differentmethods used for optimal programming for individuals who undergo CRT device implantations.