Mainstream primary school teachers generally acknowledge the need to implement adaptive teaching; however, meeting a variety of students' needs is a challenge. Studies have addressed the conditions under which teachers attribute their (in)capacities, but these have mainly involved vignettes. Therefore, it remains unknown whether teachers are capable of meeting their own students' needs and what is of help or hindrance to them. The current study drawn from survey data obtained from 108 Dutch teachers addresses teacher-perceived (in)capacities to meet their students' needs and perceived sources of help or hindrance in meeting them. Teachers' self-efficacy beliefs were expected to partly explain teachers' capacity. Results show that teachers feel fairly adequate in meeting students' needs. They discern four sources of help or hindrance to which teachers attribute their success, including the teacher him/herself, student characteristics and school/working conditions. Attributions at the teacher and school levels were mostly related to teacher-perceived capacities rather than to teachers' self-efficacy beliefs.