AbstractAccurate theoretical expressions for Herman‐Wallis factors for the pure rotational, fundamental and first two overtone vibration‐rotational bands have been derived. These are expressed for arbitrary rotational quantum numbers in terms of the Dunham potential parameters and the coefficients of a general operator represented by a power series expansion. The inclusion of higher order corrections in a consistent way reduces the discrepancy reported by previous workers for H2between results obatined numerically and analytically. The present expressions are of sufficient accuracy to enable one to obtain precise experimental values for the anisotropy of the polarizability and its derivatives from an analysis of Raman line intensit