The tools of translation memories and machine translation can be viewed as (not) being able to draw on different aspects of context that are relevant to a particular translation project, such as bilingual text, portions of a text, versions of a text, related text, or extralinguistic context. The aspects of context that the tools can indeed draw on and how well they do so highlight their most important benefits, whereas the aspects of context that the tools may fail to draw on reveal their weaknesses. In cases where, depending on the context, a piece of text being translated may have more than one meaning or a translation of a piece of text may be rendered in more than one way, the contexts the tools are able to draw on are critical. An analysis of different kinds of context in different applications highlights the circumstances in which users of TM and MT tools may risk accepting semantically and lexically undesirable output, as well as when TM tool users may risk inputting contextually inappropriate translations. Further, context is an important consideration when integrating MT output into TM tools. Although TM and MT technologies differ in how they produce translation output, end-users of both tool types may face similar contextual challenges.