The glass-forming ability and crystallization behaviour of lithium borate compositions, in the diborate to metaborate range, were studied. In particular, the nature and sequence of formation of crystalline phases and the tendency towards devitrification were investigated as functions of temperature, thermal history and batch composition. It was found that the sequence of crystalline phase formation was sensitive to all of the three latter factors, and it was observed that under certain conditions metastable defect structures of the metaborate can appear.