The identity of the teacher has been determined to influence classroom practices. Positional identity is defined as one's perception of self relative to others. This qualitative research study investigates the positional identity of five high school science teachers of different ethnicities and how their positional identities influence their classroom practices. Positional identity is thought to be determined by one's perception of how one's race, ethnicity, gender, age, religion and socioeconomic status position one relative to others. The methods of data collection included classroom observations, structured and semi-structured interviews, book club meetings, teacher journals, and researcher journals, demographic and online questionnaires. The teachers that overcame stereotypes based on race/ethnicity, gender and socioeconomic status felt empowered in their positional identities and were able to empower their students. The data also identified those teachers that struggle the most with finding their power within their positional identities were the immigrants that were not able to merge their personal identities within the pre-determined social positions they encountered in this society. The empowerment or powerlessness of the science teachers' positional identities impacted instruction and practices within the science classroom. [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.]