‘Accounting lag’ is a term that was used by Robert Kaplan and others in the course of the nineteen-eighties to suggest that the development of accounting systems lagged behind manufacturing developments. Engineers and accountants are key agents who are likely to be affected by the phenomenon of accounting lag in the process of technical change in an organization. While accounting systems at some firms may be generally anachronistic, individual decisions are taken according to more accurate criteria. Discounted cash flow methods of appraisal were investigated because it has been argued that these are more suited for the introduction of computer based systems than payback. If Management Accounting is to provide an effective counter to the operation of accounting lag, it is to be anticipated that it would provide details of new engineering systems at the time when firms are considering purchasing them.