Background: Demographic characteristics are known to influence participation in cocurricular activities. Less studied are the effects of other background characteristics. Purpose We hypothesize that considering college knowledge and students' proactive behaviors in tandem with demographics provides better models for predicting such participation. Method: We developed a questionnaire and administered it to 3,618 domestic third‐ and fourth‐year undergraduate engineering students at a large public R1 Midwestern university, yielding 860 responses. Logistic regression models predicting five types of cocurricular participation were constructed with demographic characteristics, college knowledge, and proactive behaviors in all combinations as predictors. Results: Four of five types of cocurricular participation were better modeled using factors beyond demographics. Two were better modeled using only proactive behavior as predictors and two were better modeled using demographics in combination with either college knowledge or proactive behavior. Only one type of participation could be best predicted by demographics alone. Conclusions: These findings contribute quantitative evidence establishing relationships between participation in engineering cocurricular activities and a wider range of factors than previously reported. Furthermore, they provide guidance for creating intervention programs because, unlike demographics, college knowledge and proactive behavior can be shaped by either the individual or the institution. [ABSTRACT FROM AUTHOR]