For decades, researchers have studied teacher efficacy. In the past decade or so, however, collective teacher efficacy has been at the forefront of educational research as an extension of teacher self-efficacy. Educational researchers have been studying this construct to determine its impact on student achievement, teacher quality, and school level effectiveness. While studies on collective teacher efficacy have indirectly alluded to the link between collective teacher efficacy and collective teacher effectiveness, little direct research has been conducted on the comparison between the two. To that end, this study investigated the comparison between collective teacher efficacy and collective teacher effectiveness. Established instruments, the Cultural Insight Survey and the Teacher Effectiveness Measure Framework, were used to gather data about collective teacher efficacy and collective teacher effectiveness. A random sample of teachers was used given the disparity in male and female teachers. This study investigated a comparative relationship and sought to determine if there were differences in the two constructs at the elementary, middle, and high school levels. Also, the study investigated the difference between male and female collective effectiveness scores using the Teacher Effectiveness Measure Framework. The study found that a significant relationship exists between collective teacher efficacy and effectiveness. As perceived collective teacher efficacy increases, so does collective teacher effectiveness. The element of collective teacher efficacy that most accurately predicted collective teacher effectiveness at all school levels was learning environment. As the learning environment score increased, so did collective teacher effectiveness. The difference in male and female teachers' collective effectiveness yielded that males scored slightly higher than their female counterparts. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]