This document summarizes research on the strength and behavior of cold-formed steel hollow section columns. It reviews several experimental and numerical studies that investigated the load-carrying capacity of different types of cold-formed steel hollow sections under compression, including circular hollow sections, elliptical hollow sections, rectangular hollow sections, square hollow sections, and built-up sections. The studies compared results from tests of column specimens to design standards and methods such as the Direct Strength Method. Most found that existing design approaches provide conservative strength predictions for cold-formed steel hollow section columns.