The analysis is reported of the lumped capacitance and open-circuit end effects of finite-length strip conductors in double-layer microstrip structures. Two specific configurations, namely double-layer microstrip and microstrip-with-overlay configurations, are considered. The analytical approach uses the variational technique in the Fourier transform domain in conjunction with the transverse transmission line technique. It is identified that the only parameter needed to analyse the lumped capacitances and open-circuit end effects of these microstrip structures is the admittance at the charge plane. This parameter can easily be determined from the two-wire transmission line equivalent circuit. Extensive numerical data are generated for the lumped capacitances and open-circuit end effects of the finite-length strip conductor in double-layer microstrip and microstrip-with-overlay configurations. The data presented should be useful in designing lumped elements and filters in these configurations.