The use of four periods in the school day, as opposed to six, with each period 90 minutes in length is referred to as 4 X 4 block scheduling. In Virginia, as in many states, there is increasing interest in this kind of scheduling to deliver education that meets the instructional needs of students. In 1995-96, Western Branch High School (WBHS) of the Chesapeake Public School Division (Virginia) organized the school day based on the 4 X 4 model. The school year is still divided into two semesters, but courses require only 90 instructional days, and students may take eight classes each year toward graduation. The literature on 4 X 4 block scheduling does not provide conclusive evidence for or against it because it is a relatively new approach. The evaluation of the block scheduling at WBHS studied positive and negative impacts on students, teachers, and the school administration. Data were collected to compare 1995-96 with 1994-95. Data included: a teacher survey, answered by 69% of the faculty, interviews with department heads, a survey completed by 34% of 300 students sampled, interviews with 30 students, and surveys completed by 40% of 300 parents sampled. Findings suggest concerns about the scheduling of advanced placement courses and examinations as well as other scheduling aspects. Additional staff development, the possibility of a longer school day, a review of the credits required for graduation, and the exploration of ways to help transfer students were among the recommendations for continuing the block scheduling. It is suggested that other high schools in the district try block scheduling, using either 4 X 4 or an alternate day block, as an option if students, parents, and faculty understand and support the concept. Four appendixes contain the interview format for department heads, a chart of advanced placement score increases and declines, a summary of student interviews, and a list of excess textbooks due to block scheduling. (Contains 14 charts.) (SLD)