We present improved limits on the production of massive stable charged particles in p¯p collisions using the Collider Detector at Fermilab based on an integrated luminosity of 3.54 pb−1. Both unit and fractionally charged particles are considered. Cross-section upper limits are determined for masses from 50 to 500 GeV/c2. Theoretical cross sections are used to set bounds on the mass of fermionic color triplets, sextets, octets, and decuplets as well as scalar triplets.Received 4 June 1992DOI:https://doi.org/10.1103/PhysRevD.46.R1889©1992 American Physical Society