Drilling efficiency optimization techniques are proven at reducing well costs. Unfortunately, they are often neglected by operators, even when their primary focus is to maximize revenue. Inefficiencies can inundate drilling campaigns, usually as a result of operator’s being blind to opportunity. To achieve well cost reductions, some operators will procure the cheapest available equipment. Others will go as far as designing their wells below minimum standards if they feel that the sacrifice in quality and specification is worth the risk and money saved. Inefficiencies and sub-standard designs almost always cause increased well costs, either right away, as the case is with slow drilling in typical day rate contract , or later on in the well life cycle, when costly work overs and remedial operations are required when the substandard equipment fails. Lean manufacturing has been accepted across a wide array of industries as the most proven method for optimizing efficiency and reducing operating cost. In essence, lean is the elimination of waste while maximizing value to the customer. The oil and gas industry is no exception as lean has been successfully used for improving product delivery and cost, whether its wells in the case of operators or tools and equipment in the case of service providers. Drilling, a component of the overall well construction process, can be optimized through lean concepts by removing inefficiencies, reducing required resources, minimizing costs and maintaining product quality. In recognition of the need for improving project economics world-wide, a major international oil and gas company instated a campaign to improve efficiency and reduce costs across all areas and function groups to help meet financial goals. This paper reviews how one of the company’s drilling teams adopted lean methodologies and effectively reduced the costs and days to drill wells in North Dakota in an infill development drilling campaign without sacrificing quality standards.