Design of experiments (DOE) is a scientific method for identifying the critical parameters associated with a process and thereby determining the optimal settings for these process parameters for enhanced performance and capability. It is a powerful technique employed in the improvement phase of the Six Sigma methodology as a means to improve process yield, stability, customer satisfaction and reduce process variability which results in high scrap, rework and warranty costs. This paper presents the application of DOE to a spot welding process in order to discover the key process parameters, which influence the tensile strength of welded joints. Statistical analysis was carried out to identify the process parameters, which affect the mean strength and variability in weld strength. The results of the study encouraged the engineering team within the company to extend the application of DOE to other core processes within the business as a process performance improvement technique.