The thinking machines CM-5 is one of the first of a new generation of massively parallel systems. To assess the scalabililty of the CM-5's computation adn interprocessor communication rates, we used a series of data and control networks, the node vector units, and the balance of computation and communications. At the application level, ww found the achevable communication bandwidth and processing rates to be roughly fifty percent an dforthy percent, respectively, of the coresponding theoritical peak rates. Our early assessment is that the CM-5 is scalable but that a better balance of communication and processing rates would increase its effectiveness