The study described in this report was initiated in 1987 by the PVRC Design Division Committee on Piping, Pumps and Valves under a PVRC grant to Mr. Rodabaugh following an informal request from the ASME Boiler and Pressure Vessel Committee, Working Group on Piping (WGPD) (SGD) (SC-II) to develop stress indices and stress intensification factors (i-factors) for piping system laterals that could be considered by the ASME Committee for incorporation into the Code. In this study Mr. Rodabaugh had considered all the existing information on lateral connections in concert with existing design guidance for 90 degree branch connections; and has developed compatible design guidance for lateral connections for piping system design. As a corollary bonus he has also extended the parameter range for the "B" stress indices for 90 degree branch connections from d/D = 0.5 (the present Code limit) to d/D = 1.0. Therefore, this report should be of significant interest to the B31 industrial piping code committees, as well as the ASME Boiler and Pressure Vessel Committee. Publication of this report - WRC Bulletin No. 360 was sponsored by the Committee on Piping, Pumps and Valves of the Design Division of the Pressure Vessel Research Council.