Herein, we present data from two studies of Twitter usage in different postsecondary courses with the goal of analyzing the relationships surrounding student engagement and collaboration as they intersect learning outcomes. Study 1 was conducted with 125 students taking a first-year seminar course, half of who were required to use Twitter while the other half used Ning. Study 2 was conducted with 135 students taking a large lecture general education course where Twitter participation was voluntary. Faculty in Study 1 engaged with students on Twitter in activities based on an "a priori" theoretical model, while faculty in Study 2 only engaged students sporadically on the platform. Qualitative analyses of tweets and quantitative outcomes show that faculty participation on the platform, integration of Twitter into the course based on a theoretically driven pedagogical model and requiring students to use Twitter are essential components of improved outcomes. (Contains 3 figures.)