In this article we undertake selective quantitative analyses of the demographically-sampled spoken English component of the British National Corpus (for brevity, referred to here as the Conversational Corpus). This is a subcorpus of c.4.5 million words, in which speakers and respondents are identified by such factors as gender, age, social group and geographical region. Using a corpus analysis tool developed at Lancaster University, we undertake a comparison of the vocabulary of speakers, highlighting those differences which are marked by a very high chi-squared value of difference between different sectors of the corpus according gender, age and social group. A fourth variable, that of geographical region of the United Kingdom, is not investigated in this article, although it remains a promising subject for future research. (As background we also briefly examine differences between spoken and written material in the British National Corpus (BNC).) This study is illustrative of the potentiality of the Conversational Corpus for future corpus-based research on social differentiation in the use of language. There are evident limitations, including (a) the reliance on vocabulary frequency lists, and (b) the simplicity of the transcription system employed for the spoken part of the BNC. The conclusion of the article considers future advances in the research paradigm illustrated here.