This chapter offers a comprehensive analysis of gemination in Contemporary Spoken Persian, challenging the prevailing view that gemination is primarily a feature of Arabic loanwords. Drawing on data from traditional grammars, modern linguistic studies, and acoustic analysis, the study distinguishes between lexical and post-lexical geminates, as well as between true and false geminates. It demonstrates that while Arabic borrowings contribute significantly to the presence of geminates in Persian, originally Persian words also exhibit gemination through processes such as diachronic assimilation, compensatory lengthening, and emphasis. The chapter further explores gemination in complex lexical items, onomatopoeic expressions, and colloquial speech, revealing its broader phonological and morphological roles. By integrating historical linguistics with phonetic evidence, this work repositions gemination as a dynamic and integral feature of Persian phonology rather than a marginal or foreign import.