The goals of this study are to understand different buckling modes, determine the buckling mode and maximum buckling capacity of the built-up C-channels, and evaluate the AISI-2001 Specification. For these goals, the following was conducted: 1) different buckling modes of cold-formed steel columns were investigated; 2) previous research on built-up columns and testing rigs for column buckling was reviewed; and 3) the authors' buckling test results of 42 cold-formed built-up columns were examined. The study and review help better understanding of the buckling modes and the effect of design or testing parameters on the buckling behavior. The results show inconsistencies in the calculated values by AISI-2001 as compared to the maximum capacity loads determined from the buckling tests. The orientation of the member substantially impacts the maximum load of the member.