Occupations in science, technology, engineering, and math (STEM) are growing faster than all other fields in the United States. While this is exciting, there is concern that many of these positions will go unfilled, as students in STEM are leaving their educational pursuits at an alarming rate. The following two studies provide an in-depth examination of college students' experiences in the STEM laboratory setting to better understand the influence that the perceived motivational climate has on their psychological functioning. Study 1 was designed to validate measures of climate (i.e., caring, task-involving, ego-involving) and motivational measures (i.e., effort, enjoyment) for use in the STEM laboratory setting. Results of confirmatory factor analysis (CFA) revealed that the adapted measures were valid and reliable for use in the novel context. Study 2 was designed to build upon Study 1, by examining the influence of instructor behaviors on STEM students' perceptions of the motivational climate and their adaptive (i.e., effort, enjoyment, performance and social self-esteem) and maladaptive (i.e., shame) experiences in the biology laboratory setting. Results of Study 2 revealed when instructors engaged in effective teaching behaviors, students were more likely to perceive a caring and task-involving climate and in turn, report adaptive motivational responses (i.e., increased effort, enjoyment, self-esteem; decreased shame). The goal of the combined studies was to provide psychometric support for survey measures that institutions could employ with their students to better understand their experiences, as well as identify specific behaviors that instructors could be trained to implement to foster caring and task-involving climates. [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.]