Modern English grammar is undergoing noticeable transformation, especially in pronoun usage. One of the most debated issues today is the use of singular they as a gender-neutral pronoun. Traditional grammatical rules require agreement between singular nouns and singular pronouns; however, contemporary English increasingly employs they to refer to an individual person. This article analyzes singular they as a grammatical and sociolinguistic phenomenon by examining its historical development, linguistic justification, pedagogical implications, and modern institutional acceptance. The study argues that singular they represents a natural evolution of English grammar shaped by communicative efficiency and social change rather than a violation of grammatical norms.