The invention relates to devices for performing single step assays for the determination of the presence or absence of an analyte in a liquid sample, and methods of determining the presence or absence of such analytes using such devices. Devices disclosed comprise a labeled analyte-binding reagent reversibly-immobilized on a non-porous solid material, which solid material is in physical contact with a dry porous carrier bearing an immobilized analyte-binding reagent. Also provided are quantitative assay devices.