Insight into assessors' initial impressions has the potential to advance knowledge on how assessors form dimension-based judgments and on possible biases in these ratings. Therefore, this study draws on dual process theory to build and test a model that integrates assessors' dimension ratings (i.e., systematic, slow, deliberate processing mode) with their initial impressions (i.e., intuitive, fast, automatic processing mode). Data collection started with an AC where assessors provided ratings of assessees, and an online survey of assessees' supervisors who rated their job performance. In addition, two other rater pools provided initial impressions of these assessees by evaluating extracted 2-min video clips of their AC performance. Initial impressions from both of these samples were positively related to assessors' dimension ratings, which supports assumptions from dual process theory and might explain why assessors' dimensional ratings are often undifferentiated. Initial impressions did not appear to open up the doors for biases and stereotypes based upon appearance and perceptions of liking. Instead, assessors picked up information that assessees transmitted about their personality (i.e., Conscientiousness and Emotional Stability). Implications for further research on initial impressions and AC dimension ratings are discussed.