Construction of effective actions in superspace

A functional method of calculating superspace effective actions in supersymmetric theories is developed by use of superfield functional integrals and multipole-expansion techniques. The superspace effective actions for supersymmetric QED and the supersymmetric $\mathrm{C}{\mathrm{P}}^{n-1\mathrm{}}$ model are constructed by this method without reference to component-field calculations.