The spectral norm of a Boolean function f : {0, 1} n → {−1, 1} is the sum of the absolute values of its Fourier coefficients. This quantity provides useful upper and lower bounds on the complexity of a function in areas such as learning theory, circuit complexity, and communication complexity. In this paper, we give a combinatorial characterization for the spectral norm of symmetric functions. We show that the logarithm of the spectral norm is of the same order of magnitude as r(f ) log(n/r(f )) where r(f ) = max{r 0 , r 1 }, and r 0 and r 1 are the smallest integers less than n/2 such that f (x) or f (x) · PARITY(x) is constant for all x with x i ∈ [r 0 , n − r 1 ]. We mention some applications to the decision tree and communication complexity of symmetric functions.