Data reported in this survey were collected by means of a mail survey with telephone followup. In the nationally representative sample of public school teachers, 44 percent reported there was more disruptive classroom behavior in their schools in 1986-1987 than five years before. Almost one third indicated that they had seriously considered leaving teaching because of student misbehavior. On the average, teachers estimated that about seven percent of the students they taught were habitual behavior problems. Most teachers reported that student behavior interfered with their teaching to a small extent (50 percent) or a moderate extent (26 percent). Almost 20 percent indicated that they had been threatened by a student at some time. While there are indications that teachers viewed their schools' discipline policy more favorably than they did in l980, 34 percent still regarded their schools' discipline policy as not strict enough; 28 percent regarded it as not comprehensive enough; and 50 percent indicated it was not consistently applied. 12 notes, 4 figures, and 9 tables.