Design-based science (DBS) is a science pedagogy in which new scientific knowledge and problem-solving skills are constructed in the context of designing artifacts. This paper examines whether the enactment of a DBS unit supported students' efforts to construct and transfer new science knowledge and 'designerly' problem-solving skills to the solution of a new real-world design problem in a real-world setting. One hundred and forty-nine students participated in the enactment of a DBS unit. Their understanding of the curricular content was assessed by identical pre-instructional and post-instructional written tests. They were then given a new design problem as a transfer task. There was a statistically significant increase on scores from pre-test to post-test with an effect size of 1.8. There was a stronger correlation between the scores of the transfer task and those of the post-test than with those of the pre-test; we use this finding to suggest that the knowledge that was constructed during the unit enactment supported the solution of the transfer task. This has implications for the development of science curricula that aim to lead to the construction of knowledge and skills that may be useful in extra-classroom settings. Whether participation in consecutive enactments of different DBS units increases transfer remains to be investigated in more depth.