Recent policies and programs in science education underscore a need to address "opportunity gaps" for students who are parts of minoritized social, cultural, or racial/ethnic groups. In order to implement professional learning for teachers to assist them in effectively supporting all students, it is critical to understand the classroom environment and practices that most equitably support students across different cultural, linguistic, or racial/ethnic backgrounds. This mixed-methods research examined the interplay of culturally responsive teaching practices and students' self-reports of engagement as teachers attempted to enact motivationally supportive teaching practices and ambitious science teaching. Participants were 7th grade science teachers (n = 4) and their respective students (n = 102) in two school districts in two different states. Data was collected over the course of a chemistry unit from classroom video observations, lesson plans, curricular materials, and student end of class reports (ECRs); school demographic data was used to examine group-level differences between student ECRs. The most frequently used supporting strategies included teachers positioning students as knowledge generators, encouragement of use and sharing of student language, valuing of students' lived experience as evidence, and support for student belonging. The most frequently observed undermining behaviors also included undermining students' position as knowledge generators and belonging support. Teachers were less likely to use strategies (either supporting or undermining) that elicited or valued student funds of knowledge (FOK) and use of students' critical lens to solve problems. Students' experiences of the classroom indicated greater dispersion (variability) in self-reports of engagement for male and nonwhite students, particularly in terms of behavioral forms of engagement. The correlation between teacher cultural responsiveness and student engagement were less clear. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]