An assay of data gathered from 2347 users of English on their self-reported swearing conduct in English disclosed notable higher values for the 1159 native English (L1) users than for the 1165 English foreign language (LX) users. Parallel analyses on the data of the L1 and LX users disclosed that the interlocutor effect was a bit stronger amid L1 users. Swearing was reported to be most recurrent in interactions with friends, when alone, followed by interactions with family members, colleagues and strangers. Participants scoring high on Psychoticism, Extraversion and Neuroticism reported notably more swearing in English. Extraversion and Neuroticism had the strongest impact on LX users’ self-reported swearing with friends and alone while Psychoticism and Neuroticism had the strongest impact on L1 users’ self-reported swearing with strangers and with friends. The impact of sociobiographical variables (education level, age group and gender) was widely alike among L1 and LX users but was significant in more categories of interlocutors for the L1 users. It is claimed that the weaker effect of situational, psychological and sociobiographical variables on self-reported frequency of swearing among LX users of English could be related to bigger heterogeneity in their history of learning, socialisation, ability and use of English.