XML information retrieval systems differ from traditional information retrieval systems by returning relevant portions of documents, rather than entire documents. Theoretically, this should better fulfil the information needs of users, especially in situations where their information need is very complex. However, if users are going to exploit this advantage then they need a query formation interface that is both sophisticated and intuitive. This paper outlines four potential query formation interfaces: keywords, formal language, natural language and query by templates. For each interface it: outline the advantages and disadvantages, presents comparative results stemming from experiments and proposes several future research areas involving the four interfaces.