The Transportation Worker Identification Credential (TWIC) is designed to enhance security at U.S. ports. It demonstrates that the holder has passed a Transportation Security Administration security threat assessment and is required of anyone with unescorted access to a secure area at a regulated facility. This report provides the findings from an assessment of the TWIC program, along with the assessors’ recommendations. David Metz is an honorary professor in the Centre for Transport Studies at University College London and was formerly Chief Scientist at the UK Department for Transport. He is the author of Peak Car: The Future of Travel (2014) and The Limits to Travel: How Far Will You Go? (2008).