This paper draws on psycholinguistic and sociolinguistic work to explore to some extent automatic but socially mediated syntactic alignment with the aim of grasping how social perception and cognition affect the mechanisms herein included. A general alignment effect was found across social conditions and unrelated to social perceptions. Alignment extent though was affected by a range of factors, involving discerned standardness of the passage speaker's accent, participants' observed likeness to the speaker, and participants' predilection for accord as conflict resolution style. A novel web-based paradigm was employed to collect speech data from a large socially heterogeneous sample. Participants listened to one of three speakers, each with a different accent, deliver an ideologically charged diatribe. Participants then completed a picture description task to assess the degree of syntactic alignment. Finally, participants completed a comprehensive social questionnaire designed to assess a wide range of social dimensions, which were tested as predictors of alignment. Our results suggest that syntactic alignment is to some extent automatic, but socially mediated. We found an overall alignment effect across social conditions and independent of social perceptions. However, the degree of alignment was influenced by a number of factors, including the perceived standardness of the passage speaker's accent, participants' perceived similarity to the speaker, and participants' preference for compromise as a conflict management style. These findings are discussed in terms of theories of linguistic alignment and speech production.