Based on theories of social information processing and judgment formation, we investigated whether teachers' achievement expectations, achievement aspirations and judgments of achievement-relevant characteristics depend on students' ethnic and/or social backgrounds. Furthermore, we addressed whether judgments for minority students are negatively biased or judgments for majority students are positively biased. To answer these questions, we conducted an online-study with 237 primary school teachers in Germany. We employed case vignettes and experimentally varied students' ethnic and social backgrounds by means of assigning specific first names. Teachers were asked to rate specific achievement expectations and achievement aspirations (grades for main subjects) for each student as well as provide judgments of achievement-relevant characteristics (general abilities, willingness to put in effort, qualification for a higher secondary school). Results from multi- and univariate analyses of variance with subsequent contrast analyses revealed significant differences in teachers' judgments for all considered characteristics dependent on students' ethnic and social backgrounds. Results suggested that teachers' achievement expectations and achievement aspirations are quite accurate for students with an immigrant background, but that teachers overestimate students without an immigration background and with high socioeconomic status. Findings are discussed with regard to automated and controlled information processes.