Five informal science-related writing tasks of 374 seventh grade boys and girls (ages 12-13) from two US schools were analysed. Both differences and similarities were revealed between boys’ and girls’ preferences and performance. Almost 60% of the boys preferred to write about science-related inventions, whereas girls’ preferences were distributed among the different tasks. Content differences revealed a more practical perception of science among girls as opposed to a more imaginative one among boys. The boys wrote more formally and concisely whereas the girls produced longer written works, provided more detailed information and seemed to adapt better to the style demand of the different tasks. The quality of boys’ and girls’ writing, as reflected by the scope of the contents and the depth of treatment, was relatively poor. Boys and girls alike revealed curiosity concerning the heart and the brain, its structure and functioning, a desire to find a cure for cancer and AIDS, and a great concern for the environment. The integration of science and writing reflects a new perspective on gender differences in both science and writing, where the gap seems to be narrower than that typically found when science and writing are examined separately. Authentic writing examples are provided and implications for classroom practices aimed at enhancing communication skills and minimising gender-related difference in both science and writing are discussed.