Harry Potter series using Noam Chomsky’s Transformational Grammar Theory. Specifically, the study sought to find out the writing style of J. K. Rowling in her Harry Potter series in terms of sentence structure, tense of the verb, and voice of the verb; and examine the deep structure writing style of J. K. Rowling in her Harry Potter series in terms of number of kernel sentences in transformed sentences, connectives used, and reductions used.