The PACSCL 'Hidden Collections' project aims to process and make accessible approximately 200 hidden archival collections in Philadelphia, which are currently unprocessed or under-processed and not research-ready. Funded by the Council on Library and Information Resources, the project involves collaboration among 23 member libraries to arrange, describe, and create finding aids for these collections, enhancing their discoverability. After one year, 74 collections have been processed, revealing valuable historical resources related to various fields including arts, history, and science.