Healthy eating in women of childbearing age is critical to the health of future generations. Interventions that increase women’s dietary self-efficacy may be particularly effective at improving healthy eating. However, no validated tool exists to measure self-efficacy for healthy eating in this specific population. We therefore designed a new questionnaire (the 8-Item Self-Efficacy for Healthy Diet Scale) using a think-aloud study and expert panel consultation. We then pilot-tested the 8-Item Self-Efficacy for Healthy Diet Scale in an interviewer-administered survey of 94 women recruited primarily from community settings. The 8-Item Self-Efficacy for Healthy Diet Scale is an 8-item measure of self-efficacy for healthy eating with promising psychometric properties including internal consistency, convergent, criterion and divergent validity.