A unit on probability and statistics was introduced into 18 ninth-grade general mathematics classes. The effects of this unit on teacher attitude, student attitude, and student achievement in several selected mathematical areas were investigated. The experimental group of 18 classes and a comparison group of 17 classes were tested before and after the unit was taught. The results indicate that (1) the only change in teacher attitude was that those who taught the course became more positive about the ability of ninth-graders to learn statistical concepts; (2) the unit was not effective in improving computational skills, but did improve proficiency in other mathematical areas; and (3) the unit was ineffective in promoting an improved student attitude toward mathematics. (CT)