Motivation in simultaneous L2 learning situations is an area of research largely overlooked and studies from contexts where people are engaged in learning more than one L2 are rare. In their large-scale Hungarian research, Dornyei, Csizer and Nemeth found that pupils' positive attitudes to one L2 could cause interferences with attitudes to others, with English being the greatest source of such interference. In this article it is suggested that, as an alternative to interference, Markus and Nurius' theory of the working self-concept may offer a theoretically more coherent explanation for between-language effects in situations of simultaneous learning. Using a specially designed instrument, three hypotheses were tested for a sample of Swedish pupils actively engaged in learning two L2s. First, it was hypothesised that learners would have separate L2 self-concepts as speakers of different L2s, secondly, that FL self-concepts would be interpreted negatively in relation to English self-concepts and, finally, that a high degree of FL-to-English negative self-concept referencing would be associated with low FL motivation. Whilst tentative support was found for all three hypotheses, with negative effects of English being most noticeable among boys, the results need to be followed up by further research employing more exacting methodologies. (Contains 2 tables.)