A forum on microseismic technology took place on 22–24 January 2013 in Napa, California. It was the second of its kind; the first was held in April 2008 at Ucross, Wyoming, whose purpose was to bring together industry experts and capture the state of the art at the time. This year, the focus was on identifying and understanding the differences between data recorded at or near the earth's surface and data recorded in deep boreholes. To give the field the greatest possible impetus, attendants were selected based on their contribution potential with respect to the scope of the forum. From 160 applicants, a total of 74 attendees was selected, out of which 27 presented orally and eight presented posters. The forum's scope was addressed over two busy days with sessions on case studies, feasibility studies, processing, uncertainties, and the road ahead. Two lunchtime presentations addressed subjects of wide interest not covered in these sessions. No proceedings were planned in order to encourage the sharing of otherwise confidential information.