Daniel T. O'Brien is Associate Professor in the School of Public Policy and Urban Affairs and the School of Criminology and Criminal Justice at Northeastern University. He focuses on the use of modern digital data sets to better understand urban processes, including crime, education, transportation, public health, and neighborhood social dynamics. He is Director of the Boston Area Research Initiative, in which capacity he has worked extensively to build effective models of research-policy collaboration that help us to better understand and serve cities. His previous book, The Urban Commons, captures the intersection of his efforts to advance both science and practice in cities, using the study of "custodianship" in neighborhoods through Boston's 311 system to illustrate the potential of cross-sector collaborations in urban informatics.