Data for the study were collected by means of 913 questionnaires mailed to a sample of correctional facilities. Usable responses were received from 77.4 percent of the sample. Findings documented 383,328 juveniles in secure juvenile detention centers during 1978; 170,714 in adult jails; and 11,592 in adult lockups. In view of the response rate, researchers determined an overall estimate of 479,908 juveniles who are held in adult jails or lockups during 1978. These projections are based upon linear extrapolation from the data. The rate of suicide among juveniles in adult jails during 1978 is 12.3 per 100,000 which is 4.6 times larger than the suicide rate of 2.7 per 100,000 among youth in the general population during 1977. The rate of suicide among juveniles in adult lockups is 8.6 per 100,000 which is more than 3 times larger than the rate of 1.7 among children in the general population. Unexpectedly, researchers found the suicide rate among juveniles in juvenile detention facilities is only 1.6 per 100,000, which is lower than that of the general population. The suicide rate of juveniles in adult jails is almost 7.7 times larger than that of juvenile detention centers; similarly, the suicide rate among juveniles in adult lockups is more than 5 times larger than that of juvenile detention facilities. Since data suggest that the policy of incarcerating children in adult facilities may be contributing to a relatively high rate of suicide among those children, the study recommends that every effort be made to prohibit the jailing of juveniles. Footnotes are included. Study instruments and approximately 100 references are appended.