This paper will discuss creating custom break iterators for International Components for Unicode (ICU) a popular internationalization toolkit. ICU for Java and ICU for C/C++ provide break iterators to be used for character, word, and line-breaking. These iterators are useful for parsing text - for example, extracting words for a search engine or implementing a word-wrap feature in a text editor.The break iterators supplied are sufficient for many purposes, but some implementors may wish to use their own customized iterators. This paper will first discuss the default break iterators supplied by ICU for Java and C/C++ and how they are implemented. Next, the paper will cover how the existing iterators can be extended or replaced to meet an application-specific requirement.