The use of cellphones in conversations is ubiquitous. Although the overarching view of the social effects of cellphones in conversations appears to be negative, some research has also reported positive outcomes. The Cellphone Relevance Hypothesis predicts that effects of cellphone use on conversational satisfaction depend on the function of cellphones within a conversation. When a conversation partner integrates cellphone use into the conversation (integral use), conversational satisfaction is predicted to be higher than when the cellphone is used for a purpose unrelated to the conversation (incidental use). Two vignette studies provide support for the Cellphone Relevance Hypothesis and specify boundary conditions of the cellphone effect based on the involvement of respondents.