The paper outlines theory and practical applications of shunt varactor loaded metamaterial lines. The traditional metamaterial line is loaded with an additional shunt varactor to get tunable band-pass characteristics. Design equations are developed to synthesize a generalized metamaterial line with arbitrary impedance, phase, and bandpass response characteristics. To illustrate the concept, two compact reconfigurable microwave devices including a Wilkinson power divider with a tunable band-pass response and a tunable phase shifter were designed and fabricated.