Eighty-seven percent of black adolescent males attending an inner-city junior high school and senior high school in Baltimore report that they have had sexual intercourse. Eighty percent of the sexually experienced teenagers have used a contraceptive method--and 60 percent used one at last intercourse. Contraceptive practice is characterized by heavy reliance on male methods: Of those using a method at last intercourse, 41 percent relied on the condom; 15 percent, on withdrawal; and 14 percent, on a combination of male and female methods. Use of female methods alone (mostly the pill) accounted for 28 percent of contraceptive practice at last intercourse. Nine-tenths of the teenagers have heard of the pill and condom, but far smaller majorities have heard of the IUD and diaphragm (about three-fifths each). In general, this population regards the condom as comparable in effectiveness to the pill. More than two-fifths of those recognizing these methods believe the pill--and the condom--to be "very good" at preventing pregnancy, and one-fifth believe that about the IUD and diaphragm. Nearly four in 10 mistakenly believe that they need a parent's permission to attend a birth control clinic, while slightly more than half think they need permission to buy nonprescription contraceptives in a drugstore . Although nearly nine in 10 respondents recognize that boys share a responsibility for preventing pregnancy when they have sex, more than half are willing to tolerate unprotected coitus. Most wish to delay parenthood until their early 20s, but many of these adolescents appear to hold attitudes conducive to out-of- wedlock conception.(ABSTRACT TRUNCATED AT 250 WORDS)