A new treatment of Bose-Einstein correlations is incorporated in a space-time parton-shower model for ${e}^{+}{e}^{\ensuremath{-}}$ annihilation into hadrons. Two alternative algorithms are discussed, and we use a simple calculable model to demonstrate that they reproduce successfully the size of the hadron emission region. One of the algorithms is used to calculate two-pion correlations in ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{Z}^{0}\ensuremath{\rightarrow}\mathrm{hadrons}$ and ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{W}^{+}{W}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{hadrons}.$ Results are shown with and without resonance decays, for correlations along and transverse to the thrust jet axis in these two classes of events.