Transition probability determinations are reported for the 2s2 1 S - 2s2p 1P transition in Be I and B II, based on lifetime measurements made by beam-foil excitation. The lifetimes were extracted by the ANDC method, which incorporates cascade-related decay curves into the analysis of the primary decay curve, thus accounting for the effects of cascade repopulation. The results are of higher precision than earlier measurements and improve the agreement with recent theoretical calculations.