The study analysed errors in the use of coordinative conjunctions in the written English of Senior Secondary One (SS1) students in Makurdi Local Government Area of Benue State, Nigeria, with specific focus on the influence of academic discipline and gender. The ex-post-facto research design was adopted for the study. A sample of 100 students, consisting of 50 males and 50 females, was selected using the multi-stage sampling procedure. The instrument used was Test of Use of Coordinative Conjunctions in English (r=0.81). Data collected were analysed using descriptive statistics of frequency counts, percentages, mean, and standard deviation to answer the research questions, while inferential statistics using t-test was employed to test the hypotheses. Error percentages were categorised as low (0–39%), moderate (40–49%), and high (50% and above). The findings revealed that academic discipline had a significant positive influence on students’ use of coordinators, with Arts students recording a higher cluster mean score (30.41%) than Science students (19.81%). The results also showed that gender significantly influenced students’ use of coordinators, as female students achieved a higher cluster mean score (27.60) than their male counterparts (21.88). Based on these findings, it was concluded that students’ competence in the use of coordinative conjunctions is significantly influenced by both academic discipline and gender, with Arts students and female students demonstrating superior performance. It was, therefore, recommended that English language teachers adopt disciplin esensitive and gender-responsive instructional strategies to improve students’ mastery of coordinative conjunctions, particularly among science and male students.