Members of the House of Lords are not required to provide information about their ethnicity, religious beliefs or any disabilities they may have. However, there is continued interest in the representativeness of the House, as currently composed. This Library Note provides background information on this subject: it summarises existing research on the representation in the House of Lords of minority ethnic groups, religions and disability, and sets out some of the challenges in collecting and interpreting this information. To provide further context, the Note charts some of key developments in appointments to the House. The Note concludes with consideration of the meaning of representation and how this applies to the House of Lords.