Background: Studies of engagement in meaningful activity often focus on a short period during the afternoon. The question arises whether this produces different results from studies covering the whole day. Methods: Data collected for 18 individuals using a 20-s momentary time-sample from 08:00 to 19:00 over a number of days for each person were analysed. Duration of behaviours was compared when estimated from a 2-h period between 16:00 and 18:00 and the period 08:00-16:00 and 18:00-19:00. Results: No significant differences at P less than 0.01 were found for engagement in meaningful activity, two-way interaction or 24 of the 26 behaviour codes used. Longer duration during the period 16:00-18:00 was found for personal care, which includes eating, and for neutral staff contact in institutions only. No differences were found for any code in housing. Conclusion: Observation of activity during the period before and during the evening meal by momentary time-sampling can be used to estimate overall levels of engagement in meaningful activity, two-way interaction and total staff contact, together with other behaviours, with the exception of personal care and neutral contact from staff in institutional settings. Further research is needed to confirm this result.