A field study in ten homes was conducted to understand what influences users' acceptability of notifications in the home environment. The key finding is that perceived message urgency is the primary indicator of acceptability of notifications in the home-if people think a message is urgent, they want the message to be shown immediately, regardless of what they are doing at the time of notification. The study also shows that the acceptability of low-urgent and medium-urgent messages could be improved by taking into account mental activity load at the time of notification. No effect of physical activity was found on acceptability. The results suggest that to improve the scheduling of notifications in the home, notification systems need a mechanism assessing both the message urgency and the mental activity load, whereas physical activity can be ignored. From a methodological point of view, it is difficult to measure acceptability of notifications in a realistic setting, given the need to balance experimental control with realistic context. The present paper suggests a way to introduce controlled notifications and subjective measurements of acceptability in homes.