An objective selection protocol identified 25 Ph.D. theses from Welsh universities in the period 2003-2008 which are relevant to the field of second language acquisition. Most of these fall into three broad subject areas: language in school, acquisition and assessment of spoken language, and lexical issues. The last of these encompasses the majority of theses reviewed here, and includes studies of vocabulary assessment, collocation and association, and the organisation of the bilingual lexicon. Research methods vary greatly, from classroom observations and questionnaires to lexical decision tasks and ERP (event-related potentials) techniques, and the stronger Ph.D.s tend to use mixed-methods research design. One persistent theme is that confounding complexities emerge from even the most specific and precise experimental studies. The most valuable doctoral research here recognises that its role is to investigate, with academic rigour, well-defined aspects of those complexities, and to clearly state its position in a larger investigative context.