The Mobility Analytics from Spatial and Social Data (MASS) 2015 focuses on mobility analytics taking both spatial and social dimensions of data into consideration to be colocated with The IEEE International Conference on Data Mining (ICDM) 2015, soliciting experimental and theoretical work on social networks and spatial data mining and analysis with a particular interest in those studies in connecting the two dimensions, which maps online content to offline world, to analyze user mobility and behaviors. Social and spatial environments are fundamental components of our daily life. Recent developments in both social networks and spatial services have advanced significantly thanks to the prevalence of the online social platforms, smart devices, and geo-positioning components. The availability of considerable and increasing data with social and spatial dimensions, which pose new challenges, have been attracting attentions from research communities, where previous studies used to mainly examine both domains separately. However, social and spatial processes interact dramatically. For instance, joint actions happen within space and social factors such as population migration or even just interacting with friends on a geo-enabled smartphone. The joint actions pose challenges to bridge network space where social relationships connect actors, geographic space where each actor or behavior is geo-referenced, and complex attributes that consist of actor or geo-location context. A growing number of researchers realize potential applications of mobility analytics methods to geographically embedded social networks, which call for the support of spatial social data mining and analysis in integrated tools, especially those capable to process data at a large scale.