Lateral flow assay devices and methods for detecting a first member of a specific binding pair in a sample which comprises a plurality of nonspecific binding pair members are adapted for two step determinations. In one embodiment, a two step lateral flow assay method for identifying IgE antibodies in a sample comprises applying a sample to a sample port of a device, wherein the device is adapted to deliver the sample to a lateral flow matrix having a plurality of IgE antigen species immobilized at respective positions at a first location The two step method further comprises allowing the sample to travel along the lateral flow matrix through the immobilized plurality of IgE antigen species to a second location downstream of the first location, applying liquid buffer to the lateral flow matrix to mobilize labeled reagent which is adapted to bind anti-IgE antibody and is dried on the lateral flow matrix at a location upstream of the delivery of the filtered sample to the lateral flow matrix, and allowing labeled reagent mobilized by the liquid buffer to travel along the lateral flow matrix through the immobilized plurality of IgE antigen species to a location downstream of the firstlocation. Further embodiments comprise additional lateral flow immunoassay devices and methods for identifying IgE antibodies in a sample.