Multiparty communication and proactive communication have each been studied extensively, but separately. A combinatorial approach would be to investigate proactive communication in a multiparty settings, aiming to support effective collaboration by leveraging the benefits of both. In this paper, we take a first attempt along this direction, providing formal definitions for multiparty proactive performatives. Such performatives not only result in an exchange of knowledge among teammates, but also in an increased awareness about teammates? mental states which can initiate additional helpful behaviors.