The MobileDM 2015 workshop is an international forum for researchers and practitioners to present innovative ideas and results on all aspects of mobile data mining, in particular spatial-temporal data mining, user modeling and targeting in mobile environment, user behavior prediction (e.g. POI recommendation, purchase prediction for mobile ecommerce), recommendation algorithms and recommender systems for products or services in consumer end, mobile data mining for mobile search and privacy issues in mobile data mining. The workshop aims to attract and bring together frontier ideas in the mobile data mining domain from both academic and industry space. Besides research paper presentations, the workshop will feature an Invited Talk (keynote) and a Panel Discussion session. The workshop will be held in the Atlantic City, NJ, USA in November 2015, in conjunction with the IEEE International Conference on Data Mining 2015 (http://icdm2015.stonybrook.edu/ ).