The study investigates beliefs, attitudes and practices of 101 monolingual and multilingual therapists in their interactions with multilingual patients. Mothertongue adopted a mixed-method approach, using an on-line questionnaire with 27 closed questions which were analysed quantitatively and informed questions in interviews with one monolingual and two multilingual therapists. A principal component analysis yielded a four-factor solution accounting for 41% of the variance. The first dimension, which explained 17% of variance, reflects therapists’ attunement towards their bilingual patients (i.e. attunement versus collusion). Further analysis showed that the 18 monolingual therapists differed significantly from their 83 bi- or multilingual peers on this dimension. The follow up interviews confirmed this result. Recommendations based on these findings are made for psychotherapy training and supervision to attend to a range of issues including: the psychological and therapeutic functions of multi/bilingualism; practice in making formulations in different languages; the creative therapeutic potential of the language gap.