Canadian post-secondary classrooms are linguistically diverse. This diversity comes from immigration, more access to higher education for marginalized and minority groups, and international student recruitment. An institute's language prerequisites serve as tools to help admissions decide who is linguistically prepared for study in English. Despite these language prerequisites, some students still need support with their language development to succeed in intense, two-year diploma programs at polytechnic institutes. The objective of this study, therefore, was to explore first-term students' language proficiency and compare differences based on language and education variables. The long-term goal of the project is to create local language diagnostics to identify and support students during their diploma programs. Participants were recruited from four different programs at a large polytechnic institute in western Canada. Reading, writing, and vocabulary tests were accompanied by a 15-item survey about language and education backgrounds. In total, 437 first-term students participated in the tests and survey. The results suggest that there are statistically significant differences between the first-term participants with an English background and those who do not have an English background. In addition, the range of scores on the tests is wider for participants with non-English backgrounds. I conclude that this range cannot be captured by language prerequisites pre-admissions. With locally developed, post-admission language assessments, diploma-crediting institutes could identify students at the lower end of the range and allocate necessary resources to provide them with early and individual language support so that they can succeed in their programs