This study examines the extent to which TOEIC Writing test scores relate to an external criterion: evaluations by linguistic laypersons of the functional adequacy of writing in the international workplace. Test-taker responses to two representative tasks from the TOEIC Writing test (e-mail requests, opinion surveys) were adapted for workplace role-play scenarios that laypersons read and evaluated in an online survey. After reading each role-play scenario, laypersons evaluated the text produced by their imagined interlocutor using functional adequacy scale items (comprehensibility, content adequacy, effectiveness, support and coherence). Overall functional adequacy evaluations were obtained by averaging the ratings for each of the two tasks. Layperson ratings of functional adequacy were strongly correlated with TOEIC Writing test scores (r = 0.76). Results suggested that test-takers’ writing performance is likely to be perceived as functionally adequate for test scores at which important decisions are typically made. Study results are discussed in terms of their implications for claims about the generalizability of TOEIC Writing test score interpretations with respect to those made in the international workplace, as well as the potential benefits, challenges, and limitations involved in this approach to validation.