We present a comparison of two new word-aligned schemes with some schemes for compressing bitmap indexes, including the well-known byte-aligned bitmap code (BBC). On both synthetic data and real application data, the new word-aligned schemes use only 50% more space, but perform logical operations on compressed data 12 times faster than BBC. The new schemes achieve this performance advantage by guaranteeing that during logical operations every machine instruction performs useful work on words rather than on bytes or bits as in BBC.