The development of reliable Food Frequency Questionnaires (FFQs) requires detailed information about the level and variation of dietary food intake of the target population. However, these data are often limited. To facilitate the development of new high quality FFQs and validation of existing FFQs, we developed a comprehensive National Dietary Assessment Reference Database (NDARD) detailing information about the level and variation in dietary food intake of people 20-70 years old in the general Dutch population. This paper describes the methods and characteristics of the population included in the NDARD database. 1063 men and 985 women agreed to participate in this research. Dietary intake data were collected using different FFQs, web-based and telephone-based 24-hour recalls, as well as blood and urine-based biomarkers. The baseline FFQ was completed by 1647 participants whose mean BMI was 26±4 kg/m2; 1117 participants completed telephone-based recalls and 1781 participants completed web-based recalls. According to the baseline FFQ, the mean energy intake was 2051±605 kcal/day. The percentage of total energy intake from protein was 15±2 En%, from carbohydrates was 43±6 En%, and from fat was 36±5 En%. This database will enable researchers to validate existing FFQs and to develop new high quality dietary assessment methods.