Abstract: Language functions as a tool to construct and maintain social identities. A successful cover letter must construct social identities of writers deemed as proper by readers. The appraisal theory which aims to study interpersonal meaning of discourses explores means by which writers/speakers align with readers/listeners. Right choices of appraisal resources should help build proper social identities of writers/speakers. By contrasting 30 English cover letters of native writers of English and 30 English cover letters of ESL learners in China, this paper finds different identities are built by these two groups in compliments of cover letters. The result suggests a new angle to teaching of English cover letters and further illustrates the important role of identity construction in pragmatic teaching of foreign languages.