The term code-mixing refers "to all cases where lexical items and grammatical features from two languages appear in one sentence". The current study examines the pattern of code-mixing that appears in the Pashto speech community.The present research investigates the influence of social factors on English code-mixing in Pashto language. First the focus of the study lies on the social factors e.g. style, interlocutors, topic, social distance, social status, and identity etc. and their influence on English code-mixing in Pashto language. The results show that, interlocutors, education, topic, context, profession and prestige etc. are the leading social factors which influence English code-mixing in Pashto language. The dominant pattern of code-mixing is insertion with nouns the most frequent code-mixing item. The study also concludes that Pashto is the dominant language of communication and used as a symbol of solidarity and social marker in Pashto speech community. This study contributes to the ever growing field of research on English code-mixing and establishes insertion as dominant pattern of English code-mixing in Pashto language.