This research investigated the use of Facebook to enhance the effectiveness of English writing and learning among English language teachers. English language learning through Facebook design was evaluated using the results from data collected from 403 completed copies of a questionnaire. The questionnaire sought responses on the problems, needs, readiness, and suggestions of the respondents—Thai teachers of English in 437 Bangkok Metropolitan Administration (BMA) schools. Seventeen BMA teachers who exhibited a keen interest in using Facebook over other social media were selected as test subjects. One facilitator was included. All participants used the English language to interact on Facebook every day for six weeks. A mixed method consisting of qualitative and quantitative approaches was employed to analyze the collected data. The frequency, percentage, and content analysis were used to analyze the qualitative data consisting of the survey questionnaires, observations on interaction through Facebook sites, in-depth interviews, participants' reflections, and self-notes. A t-test was used to analyze quantitative pre- and post-test data. The findings of this study indicated that Facebook could significantly help improve writing skills, namely accuracy, meaningfulness, clarity, and relevance. It also effectively enhanced teachers' English learning attributes, namely fluency, confidence, satisfaction, value, and self-efficacy belief. Keywords: English language, Facebook, learning through Facebook, teacher development