This paper deals with factors of stress concentrations in plates of finite width with central circular holes loaded through pins or rivets. Two sets of results are presented, one from oversize aluminum specimens in which the stresses were determined from strain-gage measurements, the other, from photoelastic tests with small bakelite models. The two investigations were conceived and executed independently. The tests involving the use of strain gages were made at Aluminum Research Laboratories and the photoelastic tests were made at the Photoelastic Laboratory of the Carnegie Institute of Technology. While most of the tests involved plates loaded through a single pin in a hole on the longitudinal center line of the plate, several tests were made on plates loaded through two pins symmetrically situated about the center line of the plate. Numerical values for the stress-concentration factor k are given for ratios of hole diameter to width of plate (2r/D) ranging from 0.086 to 0.76.