During the kindergarten years and until shortly before school start, there are no gender differences in (precursors of) mathematical competencies or mathematics-related motivation. Shortly after school entry, however, boys are already superior to their female peers in mathematics-related competencies and motivation. We investigated in a cross-sectional study two aspects of process quality in kindergarten that can favorably influence the development of mathematics-related motivation, especially of girls: the frequency of offers of mathematics- and science-related activities and a high-quality attachment relationship with the teacher. In 135 independent dyads, the quality of attachment between kindergarten teacher and child was assessed by a one and a half-hour standardized observation (Attachment Q-Set). The teacher provided information on how often she provides mathematics- and science-related activities. The children were asked about their mathematics-related motivation and precursors of mathematical competencies were measured using a standardized test. Results show, in line with existing studies, that girls and boys did not yet differ in their precursors of mathematical competencies and mathematics-related motivation at the end of kindergarten. Girls were involved in significantly higher quality attachment relationships with their teachers than boys. While girls' mathematics-related motivation increased with the frequency of the provision of relevant activities, it did not play a role for boys' motivation. We discuss (a) how teachers can be encouraged to offer mathematics-and science-related activities more often and (b) whether a comparable quality of attachment would be shown for boys as for girls if the kindergarten teacher were male.