Economic forecasts predict an unprecedented shortage of STEM workers in the United States. This study examined the vocational anticipatory socialization factors and classroom stratagems influencing middle school students' science, technology, engineering and mathematics (STEM) career development. Student attitudes towards STEM content areas and related career aspirations were measured. Parental, peer, media, out-of-school time activities and physical school environmental influences were examined along with teacher and school counselor capacities. The results showed middle schools were not actively engaging in STEM identity formation and career development practices nor were they providing out-of-school time STEM activities for their students. Parents, peers and the use of the online learning platform, Learning Blade did, however, have significant influences on students' STEM career development. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]