Task value has a considerable effect on one's interest, motivation, and strategies in learning. Additionally, the social contexts in which a learner studies, such as subject specialization and gender, may potentially influence how successfully one learns. The purpose of this quantitative study is to examine the relationship between task value and social factors, which were mediated by three types of learning strategy, and students' test performance in English. A questionnaire survey was conducted with 776 Grade 11 EFL vocational high school students in Taiwan. The path model revealed that the participants' English test scores were strongly influenced by the task value. Only metacognitive and cognitive strategies mediated the relationship between task value and English test score. Emotion control strategies did not mediate the relationship between them. Students' subject specialization had a direct influence on students' English test score, but the learning strategies did not play a mediating role between them.