摘要:Vocabulary learning strategies play an important role in vocabulary learning. Admittedly, lack of vocabulary knowledge will have an effect over all four of language skills: listening, reading, writing, and speaking. In addition, vocabulary learning and word retention are always the problems encountered by students at university. This study, hence, investigates ESL students studying teaching English as a second language in Universiti Putra Malaysia. This investigation attempts to understand the influence of informal language learning environment (parents and home environment) on the vocabulary learning strategies. This paper describes how mediating agents interfere in acquiring vocabulary learning strategies of ESL students or support them. The present study adopts the qualitative method. The researcher gathered data through in depth interviews and used open coding to code the data as well as constant comparative methods to analyze the data with ten students at the Faculty of Educational Studies in UPM. In order to the significance of mediating agents, the data revealed that parents' views of the importance of English are factors that elevate the process of learning vocabulary in all ten interviews. However, the information collected from the interviews showed that their parents had different perceptions on the learning of the English language due to their education level. Besides, language teachers have an effect on the students' beliefs, behaviors, and their choice of VLSs. Other contributors are affecting the vocabulary learning strategies were classroom and peers.