SUMMARY Microseismic monitoring is attracting great interest due to the application of passive seismic to shale play completion activities and the successful expansion of the method from downhole to surface and near-surface acquisition geometries. Fundamental to this application is the science behind the interpretations: The inherent capabilities and limitations of downhole, surface and near-surface recording systems and the processing and imaging applications enabled by these recordings must be appreciated to understand the results. These considerations inform issues such as: microseismic event detectability and position uncertainty; the characterization of geological features; sensitivity to hydraulic fracturing methods; rock failure modes; and well to pad to field-wide implications of large scale ‘horizontally drill and hydraulically fracture’ development programs.