The interactions predicted by cross-species conservation were at least as accurate as we had assumed in our simulations. On the other hand, their power to prioritize interactions is dependent on the network coverage in other species, and the long-term viability of this approach will depend on obtaining greater numbers of predictions than the 1,294 that are currently available. As interactome maps progress across an ever-widening array of species, these maps might be dynamically cross-compared to continually generate sufficient numbers of candidate interactions for testing. The second set of predictions, made by integrating various lines of evidence, had a lower success rate than the predictions based solely on conservation. Their potential utility is higher, however, since the number of available predictions is nearly 20 times that of the conservation-based predictions and could be increased further by including lower confidence predictions. Even with a lower success rate, the performance of the integrated classifier was superior to the best theoretical predictor we simulated.