Although Americans have long accepted the fact that blacks and other minorities are highly overrepresented in prisons, the actual extent of that overrepresentation and its causes and effects have gone unnoticed. Recent data reveal a nationwide pattern of vastly disproportionate incarceration rates for blacks and whites. For example, the incarceration rate for whites increased from about 46.3 per 100,000 to about 65.1 from 1973 to 1979, while the black incarceration rate rose from about 368 to 544.1 per 100,000 during the same period. When the sex of prisoners is considered, the problem is found to be even worse than these statistics indicate. Black males composed only 5.4 percent of the general population in 1978, yet 45.7 percent of all prisoners were black males. Thus, a significant proportion of black males and probably an even larger percentage of urban black males are imprisoned sometime during their lives. Nevertheless, almost no attention is currently being brought to bear on this problem. Arguments that blacks are imprisoned more often because their crimes are more serious or because they commit more crimes are not persuasive. Dozens of studies suggest that racial discrimination in the criminal justice process is a significant factor in determining racially disproportionate rates of incarceration. The historical record indicates that the disproportionate imprisonment of blacks is part of the legacy of slavery. There is an urgent and long overdue need for citizens, criminal justice officials, and others to join in confronting these issues. Tables and footnotes are provided. (Author abstract modified)