jMWE is a Java library for constructing and testing Multi-Word Expression detectors. The library has three main facilities: (1) a detector API, (2) a MWE index facility, and (3) a test harness. This is version 1.0.0 of the library. It contains the source code, compiled binary files, javadocs, a user's manual (pdf), and data for constructing a default MWE index. The freely available version of jMWE is licensed for use for non-commercial purposes only, as long as proper acknowledgment is made. Details can be found in the license, which is included at the end of this document. The copyright on the software is owned by MIT; if you wish to use the software for commercial purposes, please contact the MIT Technology Licensing Office for more information on how to obtain a commercial license.