We introduce in this chapter a new area in PID controllers, which is called multiresolution PID (MRPID). Basically, a MRPID controller uses wavelet theory for the decomposition of the tracking error signal. We present a general error function in terms of partial errors which gives us the various frequencies appearing in the general errors. Once we obtain the spectrum of the error signal, we divide the error at frequencies that are weighted by gains proposed by the designer. We can say that the MRPID is a generalization of conventional PID controller in the sense that the error decomposition is not only limited to three terms.