Summary.Objective tests of attainment in physics, chemistry, and biology were administered to over three‐hundred grammar‐school pupils, together with a battery of verbal, number and spatial tests. A factorial analysis yielded the following results:1The tests of physics, chemistry, and biology formed a group factor over and above a general factor.2Verbal, spatial and numerical group factors were also found.3Attainment in science, as measured by the objective tests, is dependent upon (a) the general factor, and (b) the scientific group factor.4In addition, attainment in physics (though not in chemistry and biology) depends to some extent on the spatial factor.5Again, for girls, attainment in biology depends to some extent on the verbal factor.6Attainment in all three branches of school science is independent of the number factor. Numerical ability (as measured by speeded tests of the basic arithmetical processes) has no relation to attainment in school science.7The factorial pattern underlying scientific attainment is very similar for boys and gi