Coefficient of thermal expansion (CTE) of solder alloy Sn-37% Pb was estimated by using cluster expansion method. Five phases with available experimental CTE in Sn-Pb system were employed to derive the correlation coefficient, q(i). Monte-Carlo simulation was carried out to obtain the correlation functions, xi(i). With the derived q(i) and xi(i), CTE of Sn-37% Pb was calculated, which is in excellent agreement with experiment. This study may provide a simple approach for the CTE prediction of disordered structures. (C) 2003 Kluwer Academic Publishers.