- Oklahoma, Select Committee to Investigate Indian Contracts in2
- Old Age Pension Plans and Organizations, Select Committtee to Investigate, House2
- Old Age Pension Plans, Select Committee to Investigate, House4
- Old-Age Pension System, Special Committee to Investigate, Senate3
- Oliver Wendell Holmes Devise Committee1
- Ordnance and Ammunition, Select Committee on Investigation of1
- Pacific Coast Naval Bases Joint Committee4
- Pacific Islands and Porto Rico Committee41
- Pacific Islands, Porto Rico, and Virgin Islands Committee2
- Parcel Post, General, Joint Committee to Investigate2
- Patents Commitee195
- Patents Committee, House167
- Patents Committee, Senate92
- Pay and Allowances in Army, Navy, etc., Joint Committee to Investigate1
- Pearl Harbor Attack, Joint Committee on Investigation of2
- Pensions Committee744
- Pensions Committee, House95
- Pensions Committee, Senate169
- Pershing, John J., Joint Committee on Arrangement of Welcome to1
- Petroleum Resources, Special Committee Investigating, Senate11