Almost sure estimates of the rate of convergence for the supercritical Galton-Watson process are obtained, e.g. $W - W_n = o(m^{-n/q})$ a.s. if and only if $E(Z_1^p \mid Z_0 = 1) < \infty$, where $1 < p < 2, 1/p + 1/q = 1$. Extensions to the multitype and continuous time cases are outlined.