Abstract: A dual-stream envelope feeding attachment for a sheet feeding printing press comprising a register bar centrally located in the feed path of the press between oppositely reciprocating joggers moving the envelopes into lateral registration against opposite sides of the register bar. The register bar can be assembled in a removable unit with a pair of oppositely disposed sheet riders urging the fed envelopes into contact with conveyor means on the press proximate to opposite sides of the register bar. A separator plate, having a thickness greater than the lateral width of the register bar, is mounted in alignment with the register bar on a stack feeder for initially positioning pairs of envelopes on the conveyor laterally separated from the register bar in preparation for registration thereto by the joggers.