Many studies using Self-Determination Theory (SDT) as a theoretical platform have emphasized the importance of knowing students' motivational orientations in education, and stated that autonomy-supportive or controlling learning climates are significant to determine students' motivational resources, academic achievement, and classroom engagement. Although there are many studies in the general education domain on these issues, there are few studies which focus specifically on foreign language learning especially basic language skill courses in the relevant literature. By this study, it is aimed to investigate respectively Turkish English-as-a-foreign-language (EFL) speaking course students' motivational orientations; to demonstrate the relations among intrinsic and extrinsic orientations of students, their self-perception of competence, autonomy, learning climate and classroom engagement; and lastly to examine the effects of students' perceptions of autonomy supportive or suppressive learning climates on their perceived competence, autonomous regulation, self-determined levels and engagement within the framework of SDT. In order to fulfill these aims, 142 pre-service teachers who are enrolled in EFL speaking courses at preparatory and first grades in a Turkish university were asked to complete a questionnaire to assess these constructs, followed up with oral interviews with seven specially selected participants. In brief, research findings showed that students are generally intrinsically motivated to speak English, and more self-determined motivational orientations are important predictors in determining students' competence, autonomous regulation, and their course engagement. In addition, it also revealed that instructors' autonomy supportive or controlling motivating styles were directly effective on students' self-perceptions about competence and autonomy, and had an indirect effect on students' self-determined levels and classroom engagement with the mediators, competence and autonomy. At the end of the study, in the light of research findings, some effective classroom instruction strategies and suggestions were developed to motivate learners to speak English volitionally by overcoming some psychological barriers. The following are appended: (1) Faculty permission; (2) T-test results about the participants; (3) Questionnaires; (4) Open-ended interview questions; and (5) Full path analysis model.