It has always been difficult to assess or measure the strength within a concrete member at an early age and consequently there has been no good way to know precisely when the concrete is strong enough to strip the forms. For this reason specifications have in the past been very conservative in regard to requirements for minimum ages for stripping. The conservative requirements were intended to make allowance for jobs on which there is poor site control and workmanship, or where there is little protection against heat loss from the concrete in the forms. This article describes a piece of equipment- the temperature matching curing bath (TMCB)- which cures the concrete test specimens at almost exactly the same temperature as the concrete in the structure. This is accomplished by using a thermocouple to sense the temperature within the concrete in the structure and feeding this information to an electronic unit which controls the temperature of a bath in which the test specimens are being cured. M. S. Thompson, of John Laing Research and Development Ltd., had the original concept for the TMCB. Accurate assessment of early strength development in cast-in-place or precast concrete offers benefits both to client and contractor. It provides engineers with reliable in formation on which they can judge the time to strip forms or, in the case of prestressed concrete, to transfer stress form steel to concrete. If the need arises to shorten the minimum period normally specified for these functions, the decision to do so can then be justified by reliable strength data. Earlier stripping times shorten the construction period and give more effective utilization of formwork and stressing equipment.