Arturo Bejar, then Engineering Director at Facebook, discusses his research on emotion and social media in this installment of Yale's Experts in Emotion series, directed by psychologist June Gruber. Bejar traces what drew him from engineering into studying emotional experience online, then spends the bulk of the interview on his central findings about how people express and encounter emotion through social platforms. He addresses design choices that shape emotional wellbeing at scale, drawing on his vantage point inside a major tech company. The conversation closes with his view of open questions researchers should pursue next and practical advice for students or engineers who want to work at the intersection of emotion research and technology. The format is a structured one-on-one interview with chapter markers covering his background, core discoveries, future directions, and advice, running about twenty minutes.