The presence of an enzymatically active hydrolase in a fluid sample is detected by contacting the sample with a solid-phase conjugate which is susceptible to cleavage by the hydrolase, and simultaneously or shortly thereafter, contacting the sample with an indicator which undergoes a detectable change upon the action of a reporter group. The reporter group is part of the conjugate and is liberated from it either partly or entirely by the action of the hydrolase. The indicator is susceptible to action by the reporter group only upon decoupling of the reporter group from the remainder of the conjugate, the decoupling occurring either in part or entirely upon action of the hydrolase. Also provided by this invention are various forms of a dry, self-contained test device which contains the conjugate described above plus the indicator and all other reagents and components necessary to achieve a detectable indication of the presence or absence of a catalytically active hydrolase. Preferred embodiments of the device also contain positive and negative controls.