Cities around the world are facing increasingly complex problems. These problems frequently require collaboration and information sharing across agency boundaries. In our view, information sharing can be seen as an important dimension of what is recently being called smartness in cities and enables the ability to improve decision making and day-to-day operations in urban settings. Unfortunately, what many city managers are learning is that there are important challenges to sharing information both within their city and with others. Based on nonemergency service integration initiatives in New York City and Mexico City, this article examines important benefits from and challenges to information sharing in the context of what the participants characterize as smart city initiatives, particularly in large metropolitan areas. The research question guiding this study is as follows: To what extent do previous findings about information sharing hold in the context of city initiatives, particularly in megacities? The results provide evidence on the importance of some specific characteristics of cities and megalopolises and how they affect benefits and challenges of information sharing. For instance, cities seem to have more managerial flexibility than other jurisdictions such as state governments. In addition, megalopolises have most of the necessary technical skills and financial resources needed for information sharing and, therefore, these challenges are not as relevant as in other local governments.