Developmental Steps in Child Language Acquisition: a Case Study of Persian Consonants Zahra Vafaei 1 , Ahmad R. Lotfi, PhD 2 1 MA Student, General Linguistics, Department of English, Khorasgan (Isfahan) Branch, Islamic Azad University, Isfahan, Iran 2 Instructor of Language Faculty, Department of English, Khorasgan (Isfahan) Branch, Islamic Azad University, Isfahan, Iran Abstract This article explores the acquisition of Persian consonants by a female child during her 6 to 20 months of age. The production data obtained for this study through spontaneous and elicited observations, both voice recording and keeping diary. The results suggest that the child's acquisition of consonants develops into six different steps: (a) Opening Step (from 6 to 10 months of age): during which she starts to produce meaningful utterances, three consonants /b/, /m/, and /n/ are captured in this duration. (b) Improvement Step (from 10 to 12 months of age): in this step she makes a big progress a high percentage of acquisition with seven other consonants /t/, /d/, /s/, / ∫ /, /j/, /t∫ /, and /g/ takes place around Month eleven with a high-frequency then. (c) Continuation Step (from 12 to 14 months of age): she produces a number of other consonants as /z/, /x/ ,/k/, /r/,/l/,and /h/ at the end of 14th month she can produce seventeen Persian consonants but these consonants are not as frequent as the previous step.(d) Speechlessness Step(from 14 to 16 months of age): when she produces seventeen Persian consonants although her performance deteriorates both in quality and quantity towards the end of this period due to some decline in her physical health. She goes into a long silence about 45 days and then she starts to produce some of the consonants she can produce before, and can produce /f/ sound for the first time at the end of Month 16. (e) Reopening Step (from 16 to 18 months of age): during which she starts again to produce utterances in some parts with a big shift from what she can produce before. (f) Sudden Progress Step (from 18 to 20 months of age) when she can produce whatever she can produce before also new consonants with the highest frequency. Keywords: Child Language Acquisition, Persian Consonants, Consonants Developmental Steps.