This study explores English vocabulary acquisition through social media among alumni of Kampung Inggris. Using a qualitative approach with open-ended questionnaires, it examines the types of vocabulary learners encounter, their engagement with informal sources, and the influence of social media on vocabulary retention. The study focuses only on vocabulary comprehension and does not examine productive skills like speaking or writing, so no performance-based language products are included.

Thematic analysis shows that participants often encounter informal and slang expressions through videos, captions, or conversations, which aid comprehension. Vocabulary learning via social media is generally incidental and unplanned but reinforced through repetition and context. These findings are interpreted using Krashen’s Comprehensible Input, Eraut’s Informal Learning, and Vygotsky’s Social Constructivism, highlighting the role of social interaction and context in learning.

The research suggests social media can serve as a valuable supplementary tool for vocabulary development beyond formal education. While limited to Kampung Inggris alumni in East Java using platforms like Instagram, TikTok, and YouTube, the study provides a foundation for future research to explore broader learner populations, other language skills, and performance-based assessments, offering a more comprehensive understanding of social media’s role in English acquisition.

Keywords: English vocabulary acquisition, social media learning, informal learning, thematic analysis, Kampung Inggris alumni.