The Failure Assessment Curve proposed by Harrison, Loosemore, and Milne has been rederived and interpreted in terms of an equivalent J-integral analysis. Comparison with computed values of J indicates that the curve is a good approximation to a lower-bound failure criterion for mechanical loading. The J-integral interpretation enables thermal, residual, and secondary stresses to be included within the concepts of the Failure Assessment Diagram. A procedure is introduced which transforms points on a failure diagram obtained, for instance, from a J-integral analysis, into approximately equivalent points on the Failure Assessment Diagram. This procedure is particularly useful for failure assessments involving thermal, residual, or secondary stresses where a plastic collapse parameter is not definable. The procedure assumes that a plastic stress intensity factor can be estimated. A method of assessing the severity of a mechanical load superposed on an initial constant load is also presented. Examples showing the applications and advantages of the technique are given.