Facet theory is a philosophy about the nature of the world and how this should be investigated by disciplines within social sciences and humanities. It is also a series of research design and analysis procedures. In this pocket guide we present facet theory's philosophical basis and describe and illustrate how facet theory may be used within your own qualitative and quantitative research. Facet theory is concerned with revealing the complexity of research situations and there is inevitable intricacy in our presentation of the approach. However, unusual terminology is kept to a minimum and clearly explained. As such, the book is intended to be a concise guide to those with no knowledge of facet theory. The book is a complementary text to the Mapping Sentence Pocket Guide, by the same authors and provides more details to those interested in using mapping sentences in their research.