Social media has become an important part of modern society, including in Indonesia. Its rapid development has a significant influence on various aspects of life, one of which is language. The influence of social media on the development of the Indonesian language is often seen from the emergence of new terms, the use of informal language, and the simplification of sentence structures. Language changes influenced by social media raise concerns about the decline in the ability to speak good and correct Indonesian, especially among the younger generation. This study aims to determine the influence of social media on the development of the Indonesian language among teenagers. The findings include the entry of absorption from foreign languages, especially English. Words such as "selfie", "hashtag", "viral", and "followers" are examples of new vocabulary that originally came from English but are now widely used by Indonesian speakers. The influence of social media on the development of vocabulary in Indonesian can also be seen from the use of abbreviations and acronyms. Due to character limitations on some platforms such as Twitter, users often use abbreviations to express themselves.