A study examined enrollment patterns in the Texas public school system for four cohorts of students from 1993-94 to 1996-97. The 1996-97 cohort, for example, which began with students enrolled in the 9th grade for the first time in 1993-94, was followed for 4 years through expected graduation in 1996-97. The 1993-94 cohort included first-time 9th graders in 1990-91, expected to graduate in 1993-94. In 1996-97, 203,567 students from a cohort of 224,425 completed or were still completing high school in the Texas public school system--a 5 percent increase from the completion rate for 1993-94. Completion rates vary greatly by student characteristics: in the class of 1997, students who were on-grade for their age had a much greater chance of completing high school than students who were either overage for grade when they first entered the cohort or retained sometime during high school. White students were more likely to complete high school than Hispanic or African-American students. Economically disadvantaged students had markedly lower completion rates than noneconomically disadvantaged students. Three appendixes contain a synopsis of student progress through high school over a 4-year period for the class of 1996-97; a summary of completion rates by district characteristics, 1994-97; and annual district completion rates for the class of 1996-97. Contains 15 references. (DFR)