The present disclosure provides methods and assay systems for use in spatially encoded biological assays, including assays to determine a spatial pattern of abundance, expression, and/or activity of one or more biological targets across multiple sites in a sample. In particular, the present disclosure provides methods and assay systems capable of high levels of multiplexing where reagents are provided to a biological sample in order to address tag the sites to which reagents are delivered; instrumentation capable of controlled delivery of reagents, in particular, microfluidic device based instrumentation; and a decoding scheme providing a readout that is digital in nature.