In the second year of a project investigating the ability of secondary school teachers to identify high-ability students, two questions were addressed: what student characteristics influenced teachers' judgments, and why checklists appeared to have little impact on teachers' judgments. A structured approach was developed to study student characteristics to which teachers were sensitive when making judgments on ability. This approach sought to determine the scope of teachers' knowledge of students, and how this knowledge corresponded with judgments based on students' test scores. Checklists were modified to make them more workable. Extensive classroom observations were made to establish if relevant clues to ability could emerge from day-to-day activities. A number of behavioral and motivational influences on teacher judgments, as well as those based on student test scores, were observed. It was concluded that teachers' assessments were sufficiently high for them, combined with refined checklists, to be considered relevant. (JD)