Disclosed herein is a device and methods for the rapid chemiluminescence assay of surfaces to detect the presence of microbial contamination. The device and methods are suitable for use by untrained personnel under the relatively harsh and variable conditions found in the field, for example in fast food restaurants and other food preparation areas. The chemiluminescence reaction that is the source of the analytical signal in the disclosed assay device and method is preferably based on a luciferase/luciferin system. The method for sampling disclosed herein comprises the steps of pre-wetting the sampling swab to a level below that of absorptive saturation; wiping a surface to be sampled with the swab with sufficient pressure to expel the wetting solution onto the surface; and, after reducing the pressure exerted on the sampling swab, further wiping the surface to re-absorb the moisture from the surface.