Attrition in engineering programs continues to be an important issue for universities across the country. This study examined the connection between student performance in barrier courses and persistence in engineering. Quantitative results showed that high school academic experience, student behaviors (including study habits, work habits, coping strategies), students' perceptions about faculty behavior (including teaching styles and the "weed-out" culture), the perceived culture of support in the engineering school, and motivation to succeed in engineering all impact students' performance in barrier courses. Qualitative results showed that motivation to succeed might be the reason why some students persist even when they "struggle" with barrier courses. (Contains 1 table and 3 figures.)