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This paper describes an experimental program carried out at The University of Sheffield on built-up cold-formed steel columns. The columns were constructed from individual channels and plate sections with nominal thicknesses of 1.4 mm and 2.5 mm, respectively. The columns were tested with three different connector spacing and were designed to exclude global instabilities. All the test specimens were compressed between fixed supports and each test was repeated. Therefore, a total of six built-up columns were tested. Coupon tests were extracted from the corners and the flat portions of the sections in order to determine their material properties, and detailed measurements of the out-of-plane imperfections of each specimen were recorded with a laser sensor. These data will be used for the future development of an FE model. The experiment revealed a pronounced extent of restraint and interaction between the individual components of the section while buckling, with the connector spacing having a significant effect on the observed buckling modes and, to a lesser extent, on the cross-sectional capacity