Joining the higher strength steels with arc welding demands greater care by all-designer through welder-than normally given mild steel. Proper design and welding procedures will produce crack-free welds that resist failure in service. This paper discusses weld strength allowables for high strength steels under steady and fatigue loading. It also analyzes and relates the effect of controlled heat input (preheat, welding procedure and postheat) to residual stresses, cracking, and distortion. Most of the problems experienced in welding high strength alloy steels can be predicted in advance and eliminated.