This study, focusing on reflectivity in language teacher education, was conducted with the participation of 35 preservice teachers studying at the ELT Department of Cukurova University, Turkey, in 2017-2018 academic year. The study examined the effects of jargon books (JBs) on preservice language teachers by delving into levels of reflectivity. The two sets of data of the study were collected from jargon book content and face-to-face semi-structured interviews, and display the very fact that preservice teachers mostly reflected upon course-related issues at the first and second levels, and slightly less at the third, most reflective level. Also, the findings suggest that the process of jargon book keeping was perceived as mostly positive but not free from negativity. This study has some important implications for teacher education programs and pertaining stakeholders.