This report considers the effects of the changes initiated by General Secretary Mikhail Gorbachev on the Soviet Union's probable future internal development and external behavior, and the appropriate U.S. strategy toward the Soviet Union under these conditions. The authors conclude that there are grounds for hope for considerable improvement in East-West relations, but the uncertainties are substantial enough to warrant some reservation. After identifying several alternative Western strategies for dealing with the Soviet Union, they opt for one of step-by-step engagement. The United States should engage the Soviets in a two-level dialogue. On the first level, the United States should explore the kinds of fundamental changes in the Soviet Union that would make it possible to move beyond containment and deterrence to a better balanced, more cooperative East-West relationship; to consider what would constitute evidence that such changes were taking place; and to determine how to reciprocate Soviet self-restraint and cooperation. On the second level, the United States should continue the discussions on the current U.S.-Soviet agenda — arms control, regional and bilateral issues, human rights — to which the issue of East European instability should be added, in order to help delimit and defuse the superpower competition.