This paper presents two experimental studies investigating the impact of mobile messaging during an offline conversation on relational outcomes. A first study examined the impact on impression formation. A 3 × 1 experiment revealed that phone users were perceived as significantly less polite and attentive, and that self-initiated messaging behavior led to more negative impression formation than messaging behavior in response to a notification. A second study examined the impact on perceived conversation quality and social attraction. A 2 × 2 experiment revealed that perceived conversation quality was negatively affected by co-present mobile messaging behavior, while social attraction was not. Whether persons were acquainted or not with the phone user did not moderate this relationship. •We examined whether co-present texting impacts negatively on relational outcomes.•In experiment 1, co-present texters were perceived as less polite and attentive.•In experiment 2, co-present texting caused perceptions of lower conversation quality.•Experiment 2 found no negative impact on social attraction.•Concerns over the harmful effect of co-present phone use appear warranted.