University-based Groups (that you can join)
BU Study Group supported by Mozilla Science Labs

Meetups
Greater Boston Area useR Group
R-Ladies Boston
Data Science for Social Good
STAN users of Boston/Camberville
Boston Data Education Meetup
Boston Big Data Women
Boston Data Visualization
Boston Big Data and Hadoop Learing Group
Big Data Developers Boston
Boston Predictive Analytics
Happy data hour Boston
Future of Data Boston
Cambridge Life Sciences Data Management Meetup