Measurement in behavioural epidemiology depends on high resolution and precise and accurate measures of the behaviour of interest. Few questionnaires in the adult population are able to simultaneously collect the multidimensional information that is emerging as being important in the relationship between behaviour and health. This project had two objectives: (1) to develop an adult version of the computer-delivered Multimedia Activity Recall for Children and Adolescents (MARCA), a 24-h activity recall instrument that can measure use-of-time and estimate energy expenditure and (2) to determine the test-retest reliability and convergent validity of the developed adult MARCA. Thirty-eight healthy subjects (mean+/-SD, 31.7+/-12.1 yr) completed two recalls of the adult MARCA within 24-h and accelerometer counts were measured on 30 of the subjects. Bland-Altman analysis and intraclass correlation coefficients (ICC) were used to quantify the test-retest reliability of the adult MARCA. Spearman rank correlation coefficients (rho) were used to quantify convergent validity of the adult MARCA compared to accelerometer counts. The test-retest reliability coefficients of the adult MARCA were high with intra-class coefficients ranging from 0.99 to 1.00. Moderate to strong validity was observed for physical activity level (PAL) (MET.min score of accelerometer wear time) and accelerometer counts per minute (rho=0.72). The adult MARCA is a valid and reliable self-report measure of use-of-time and energy expenditure, capable of a wide variety of flexible use-of-time analyses related to a wide range of behaviours.