This study examined the longitudinal predictability of spatial ability in late-adolescent females by retesting 11-year-old girls studied by Newcombe and Bandura at age 16. Spatial ability at age 16 was predicted longitudinally from masculinity of the ideal self on a scale of intellectually relevant attributes at age 11, wanting to be a boy at age 11, and, negatively, by feminine expressivity at age 11. No timing of puberty or lateralization effects were observed. The findings strengthen evidence that sex-related differences in spatial ability could be experientially determined, and help to focus the search for exactly how this occurs. The findings also cast doubt on the idea that sex-related differences in spatial ability could be caused by sex differences in timing of puberty or lateralization, although other biological mechanisms remain plausible.