The objective of this study is to assess selected ¯ exibility measures that have been presented in the literature , in an attempt to improve their applicability to support ¯ exibility-related manufacturing decision making, and to identify missing measures. While analysing the existing variety of ¯ exibility measurements, the paper di erentiates between the extent to which a certain ¯ exibility ... [Show full abstract] type is present in a system, to be measured on a `range' or`response or`response' dimension, and its bene® cial eect, to be assessed as a system performance. The extent of ¯ exibility is interpreted here as a cause that eventually has a bene® cial eect on the system's performance. A framework for matching the applicability of a certain ¯ exibility measure (or assessment) to the given system's needs as encountered at a certain development stage (e.g. oo-line, required, `static' ¯ exibility at the design stage, on-line, potential, `dynamic' flexibility during scheduling and control), is also provided. An exposition of some engineering ¯ exibility-related decision problems and ways to improve decisions are discussed.