The study investigated social networking site's role on improving consumer's knowledge of textile and apparel (TA) environmental sustainability. A one group pretest-posttest experiment was conducted with a convenience sample of 46 US individuals aged 18-35 (millennial cohort). The experiment included participant's interaction with TA environmental sustainability informational postings on a Facebook page for two weeks. The content of the postings was developed from available sources (e.g., YouTube, websites etc..) and covered four main aspects of TA environmental sustainability: water, energy, chemical and waste. The knowledge of the participants was measured with a study-specific textile and apparel environmental sustainability knowledge (TAESK) scale before and after the experiment. Data analysis included Wilcoxon Signed-Rank test and descriptive statistics. The findings revealed that the knowledge of the participants increased significantly after their interaction with the Facebook page postings. The study has both managerial and pedagogical implications as related to TA environmental sustainability.