Seeking to identify and activate the Receptive Vocabulary (RV) of English Language Learners (ELLs), we designed (1) an online five category multiple-choice vocabulary survey that more quickly measures vocabulary knowledge, and (2) an online creative writing task where ELLs chose RV items identified in step (1). While RV items of highly proficient ELLs cause difficulties in language production, writing tasks promote active vocabulary use and knowledge (Laufer, 2013). We designed a four stage, five week writing task based on task-induced involvement constructs where vocabulary acquisition involves need, search and evaluation (Laufer & Hulstijn, 2001). Results show (1) 74% of RV items were activated, (2) ELLs' Productive Vocabulary (PV) increased from 21% to 37%, and (3) unknown vocabulary items decreased from 25% to 14%. In future work we will measure the individual and presumably diverse use of RV. [For the complete volume of short papers, see ED572005.]