BEL is a language for representing scientific findings in the life sciences in a reusable, shareable, and computable form. BEL is designed to represent scientific findings by capturing causal and correlative relationships in context, where context can include information about the biological and experimental system in which the relationships were observed, the supporting publications cited and the process of curation. BEL is intended as a knowledge capture and interchange medium, supporting the operation of systems that integrate knowledge derived from independent efforts. The language is designed to be use-neutral, facilitating the storage and use of structured knowledge for inference by applications through a knowledge assembly process that can create computable biological networks. While BEL does not prescribe any particular assembly process or any particular knowledge format for the output of an assembly process, a suite of software components called the BEL Framework provides everything necessary to create, compile, assemble, and deliver computable knowledge models to BEL-aware applications. The current version of BEL provides the means to describe biological interactions qualitatively but not to quantify the magnitude or rate of these interactions. This limitation is by design because this quantitative information has significant variability and is not consistently reported in the literature. It is our hope that future versions of BEL can accommodate these additional data.