SOSOPT: A Toolbox for Polynomial Optimization. SOSOPT is a Matlab toolbox for formulating and solving Sum-of-Squares (SOS) polynomial optimizations. This document briefly describes the use and functionality of this toolbox. Section 1 introduces the problem formulations for SOS tests, SOS feasibility problems, SOS optimizations, and generalized SOS problems. Section 2 reviews the SOSOPT toolbox for solving these optimizations. This section includes information on toolbox installation, formulating constraints, solving SOS optimizations, and setting optimization options. Finally, Section 3 briefly reviews the connections between SOS optimizations and semide?nite programs (SDPs). It is the connection to SDPs that enables SOS optimizations to be solved in an efficient manner