Background material to seismic design aspects of the draft masonry design code DZ4210 is presented. The design approach is based on specified lateral force levels appropriate to the available but limited ductility, and on the principles of reinforced concrete section analyses adapted for low material strengths. Ultimate masonry strengths for compression, shear and flexure are based on the construction techniques and extent of supervision rather than on the strengths of the masonry constituents. Design lateral force coefficients for flexural strength depend on the characteristics of the structural system adopted and Structural Type factors (S) are proposed that are more appropriate to masonry structures than current values incorporated in the Loadings Code NZS4203. Shear failure is proscribed by the implementation of capacity design principles, though simplified procedures are allowed for structures with high flexural S factors. Brief discussion is made of so-called non-structural masonry, including veneers, partition, infill and secondary walls.