This research will develop a new theory about how groups of people work with technology. We start with the Social Brain Theory which predicts that the size of groups is limited by our ability to handle social relationships. The larger the group the more time you have to spend getting to know people. Since time for social contact is inevitably limited, relationships in larger groups are less intimate. This makes larger groups less cohesive. We want to understand how social relationships work and how technology (e.g. texting, mobile phones, SMS) might make contact easier, so groups could become larger and more cohesive. To do this we will use a second theory, Small groups as complex adaptive systems, to model how people interact and communicate with each other and via computers, mobiles, etc. We will investigate a range of different groups, such as collaborating scientists and social networks of friends, and study how and when they communicate with each other, how they identify with the group and what they think of each other. We will also run experiments with groups of different sizes with and without computer technology to help communication. This will enable us to understand why some groups of people get on better than others, and how technology helps (or hinders) their communication. The results will be a new theory that predicts how well groups of differing sizes and composition will get on and how people use computer technology for social contact. A computer model of the theory will be developed to simulate groups with different sizes and compositions. We will produce recommendation for social policy on how technology should be used in the future for Internet e-communities and requirements for the next generation of computer networks to help collaborative work, e-communities and e-society.