This article serves as an introduction to a collection of four articles on multilingual practices in speech and writing, exploring both contemporary and historical sources. It not only introduces the articles but also discusses the scope and definitions of code-switching, attitudes towards multilingual interaction and, most pertinently, the interfaces between code-switching and translation. The article shows that code-switching and translation share a number of features, yet have rarely been treated together. However, as there is a definite need to examine code-switching phenomena - particularly bilingual reiteration, which not only helps crossing language boundaries but also has other functions - from a variety of perspectives, including translation and interpreting studies, the article encourages closer collaboration between code-switching research and translation studies. It is possible to envisage a continuum of multilingual processes and products, with completely monolingual, untranslated text at one end and multilingual material with code-switching but no reiteration at the other. Along this continuum are a number of intermediate stages characterized by different types of inter-textual and intra-textual translation.