As part of an NSF funded project we developed new course materials for a general introductory statistics course designed to engage students in statistical discovery. The materials were designed to actively involve students in the design and implementation of data collection and the analysis and interpretation of the resulting data. Our overall goal was to have students begin to think like statisticians, to construct ways of thinking about data collection and analysis, to solve problems using data in context. During their development, the materials and related activities were field tested in a small special section of an introductory statistics course for two semesters. This field testing was a "proof of concept," that is that the materials could work in the laboratory setting and that the materials showed promise for improving students' learning. As a first step in evaluating these materials, students who enrolled in regular sections of the introductory course were used as a comparison group. In this paper, the development and use of the course materials will be discussed briefly. The strategy for evaluating the materials while they were being developed and analysis of students' performance on common assessment questions and the course project will be presented. In addition, the relationship between student attitudes toward statistics and students' performance will be examined. (Contains 17 tables.)