The purpose of this study is to determine English writing anxiety levels of voluntary-based English preparatory class students studying at a university. All participants were accessible, so no sampling method was used. The participants consisted of 182 voluntary-based English preparatory class students studying at a School of Foreign Languages of a public university. As a research method, mixed method (embedded design) was applied. Quantitative and qualitative data collection techniques were used together. Second Language Writing Anxiety Inventory (SLWAI) was used as a quantitative data collection tool, and document analysis was used as a qualitative data collection tool. The findings are as follows: 1- Students mostly experience moderate level of English writing anxiety which is followed by high and low anxiety levels respectively. 2- Anxiety level of male students is lower than the anxiety level of female students and students of daytime education have lower level of writing anxiety than students of evening education. 3- Students in A classes have higher level of writing anxiety than students in B classes and students with low self-perceived language proficiency level have higher level of writing anxiety than others. 4- There is no significant difference between the level of English writing anxiety and type of accommodation, socio- economic level, parental education level, parental profession and number of siblings. 5- There is no significant relationship between the students' English writing anxiety levels and reading-writing attendance.