To make this 1905 Salad (Columbia’s Salad) gluten-free, ensure the Worcestershire sauce used is certified gluten-free, as some brands may contain gluten-based ingredients such as malt vinegar. Additionally, confirm that the ham and Parmesan or Romano cheese are free from gluten-containing additives or cross-contamination, especially if purchasing pre-packaged or deli versions. All other ingredients in this recipe are naturally gluten-free.