Systems and methods are described for monitoring usage of a medicament dispenser—particularly an inhaled medicament dispenser. While operating in a low-power mode, a first sensor is monitored for a signal indicative of handling of the medicament dispenser by a user. In response to detecting such handling, the device exits the low-power mode and begins to monitor a second sensor for a signal indicative of dispensing of the medicament. The usage monitoring device can be embodied as an attachment configured to be selectively coupled to one of a variety of different inhalers including, for example, a Diskus-type inhaler and a Respimat-type inhaler.