This repository provides the official LaTeX style files (acl.sty, acl_natbib.bst) and templates for *ACL conference paper submissions. The acl.sty file configures double-column A4 layout, title/author formatting, line numbering for review copies, hyperref integration, and citation style via natbib. The acl_natbib.bst bibliography style implements author-year citation formatting with advanced features: author list truncation for >20 authors (showing 'and N others'), URL/DOI/eprint hyperlinks via urlbst integration, and proper handling of literal 'and others' entries. A regression test suite in Python validates the .bst's author-list formatting by driving the actual bibtex binary and parsing its output. This is not a software application in the traditional sense but a highly maintained, well-tested LaTeX package used by thousands of researchers annually.