Studying at university can be a very stressful experience. Although the literature provides some information regarding different sources of stress among students, studies have not addressed the issue of changes over the course progression. This study aimed to obtain a deeper understanding of the sources of stress for first-year students and whether these stressors are more prevalent at different times during the semester. A mixed-method approach was used. Content analysis was undertaken on longitudinal electronic message data, and thematic analysis was used for focus group data. Results indicated an increasing trend of stress over the semester. The major stressors identified were academic, financial/work, personal, family-related, interpersonal, social support, university/life balance and starting university. A number of stressors were found to be more prevalent at different times during the semester, including some academic-related stressors plus starting university, family-related and financial/work-related stressors. This is one of the few studies to examine the influence of timing of the levels of stress. Importantly, this study suggests that the start and end of the first semester constitute the riskiest periods for negative stress-related consequences. These results could be used to assist universities in developing student support programmes.