To extend research on online impression formation and warranting theory, the present investigation reports a Brunswick lens model analysis of Facebook profiles. Facebook users’ (n = 100) personality (i.e. extraversion, agreeableness, conscientiousness, neuroticism, openness) was self-reported. Facebook users’ profiles were then content analyzed for the presence and rate of 53 cues. Observers (n = 35), who were strangers to profile owners, estimated profile owner personality. Results indicate that observers could accurately estimate profile owners’ extraversion, agreeableness, and conscientiousness. For all personality traits except neuroticism, unique profile cues were diagnostic warrants of personality (i.e. indicative of profile owner personality and used to estimate personality by strangers). The results are discussed in relation to warranting theory, impression formation, and lens model research.