This volume contains the post-proceedings of LINEARITY 2014, the Third International Workshop on Linearity, held on July 13, 2014 in Vienna, Austria. The workshop was a one-day satellite event of FLoC 2014, the sixth Federated Logic Conference. It was held as part of the 2014 Vienna Summer of Logic. The program committee selected ten papers for presentation at LINEARITY 2014. In addition, the program included invited talks by Ian Mackie (École Polytechnique, France) and Elaine Pimentel (UFRN, Brazil). After the workshop, the authors were invited to submit a final, revised version of their paper for consideration for the post-proceedings to be published in EPTCS. The program committee selected seven papers, which are presented in this vol...