Mobile communication technology plays an increasingly pervasive role in everyday life. This study examined one aspect of this role, specifically, the effects of mobile device use on the micro-interactions of pedestrians as they approached and passed a confederate. Over 400 participants were observed in a 2 (group: mobile device vs. control) x 3 [condition: look-only (L); look and smile (LS); look, smile, and greeting (LSG)] factorial design study measuring participants' looks, smiles, nods, and greetings toward the confederates. Log-linear analyses of the dependent measures provided qualified support for the predicted decreased responsiveness from mobile device users. Specifically, a group by condition interaction on smiles showed that significantly fewer mobile device users than controls smiled at the confederates in the LSG condition. In addition, a group by sex of participant interaction on greetings indicated that significantly fewer female mobile device users offered greetings than males and females in the other conditions. The processes potentially mediating these effects are discussed and the broader influence of mobile devices on the micro-interactions of pedestrians is considered.