Research highlights the significance of spatial ability in science, technology, engineering, and mathematics (STEM). Gender differences in favor of males are observable in STEM enrollment and often also in spatial cognition. Previous studies suggest that factors such as stereotyping and working memory functioning may play an important role in this context. In a prior study, we found that children as young as preschool age already hold implicit and explicit gender stereotypes about spatial ability. Moreover, implicit gender stereotypes were linked to mental rotation accuracy in girls: stronger stereotypes favoring boys/men were associated with poorer mental rotation performance. To gain further insights into this relationship and the potential moderating role of working memory, we are conducting a follow-up study. In this study, we assess implicit stereotypes, mental rotation performance, and visuo-spatial working memory capacity in preschool girls. The relationship between implicit gender stereotypes and mental rotation performance will be tested confirmatorily. Additionally, we will evaluate whether working memory capacity moderates this relationship. Data analyses will be performed using generalized linear mixed models with the lme4 package in R. Based on an a-priori power analysis conducted with G*Power, our target sample size is N=53. Data collection is expected to be completed by February, and we anticipate having results ready to present at the conference. The study was preregistered on osf.io.