In recent decades, researchers have characterized the degradation of urban streams and developed hypotheses as to its cause.  Despite this considerable work, there remain many unanswered questions as to the actual mechanisms causing the observed changes in urban stream biotic structure and function, as well as the timeline over which changes occur.  In response, an interdisciplinary group of scientists organized the Second Symposium on Urbanization and Stream Ecology (SUSE2), held immediately prior to the annual meeting of the North American Benthological Society (NABS).  The purpose of the meeting was to (1) discuss recent research advances in the field of urban stream ecology and (2) identify outstanding research needs.  On behalf of the SUSE2 participants, I will present a summary of the meeting with an emphasis on the major research questions; these questions will hopefully guide future scientific endeavors in the field.