This research discusses slang words found in To All The Boys I’ve Loved Before film directed by Susan Johnson. This research aims to find out the types and the functions of slang words used in this film. This research is classified into descriptive qualitative research, while the data are words and phrases in the conversation. Regarding the research findings, there are five types of slang that have been found using theory of types of slang words by Allan and Burridge namely fresh and creative, flippant, imitative, acronym, and clipping. The researcher also found the functions of slang words using theory by Yanchun and Yanhong, there are three functions found namely pursuit of self-identity, emotive feeling of the slang users and the last is achieving politeness. Lastly, the implications concluded from this research is that slang is not necessarily considered as impolite because there is a conversation between a father and daughter in which both of them use slang to talk to each other. Other than that, slang seems to be really useful to know in order to be acknowledged as a part of a certain social group.