We investigate people’s attitudes towards the possible use of mobile negotiation support systems (NSS) in different social contexts and the consequences for their design. For that purpose we developed an online survey based on existing models of technology acceptance. In the questionnaire we showed five filmed scenarios of NSS use contexts. The data collected from 120 respondents, showed (a) that subjective norm is an important factor influencing the intention to use the system and (b) that the acceptance of NSS depends on the use context. Therefore, we argue that NSS should be designed not merely as tools being used in the actual negotiation but as social devices harnessing social networks to provide support in all negotiation phases.