An example for the integration of Groovy as scripting language into an application can be found at Integrating Groovy in an application - a success story
As well as Java 1.4 and the Groovy jar we also depend at runtime on the ASM library constituted of five jars (asm-2.2.jar, asm-attrs-2.2.jar, asm-analysis-2.2, asm-tree-2.2.jar, and asm-util-2.2.jar) plus the ANTLR library (antlr-2.7.5.jar). That's it. So just add these 7 jars to your classpath and away you go, you can happily embed Groovy into your application.
Alternatively, instead of several jars, you can use groovy-all-1.0-beta-x.jar included in You can use the groovy-all-x.y.z.jar from the GROOVY_HOME/embeddable directory of your distribution: this jar contains both Groovy and ASM combined in a single and convenient archive, with the ASM classes in a different namespace, so conflicts with other libraries also using ASM will be avoided Groovy installation, or find the according artifact from your Gradle / Maven / Ant+Ivy build. Please also have a look at the download section to see how to get Groovy.