This paper reports results from two field trials of TrottingPal, a mobile system that supports event information management and seamless collaboration between spectators at the trotting track. Each aspect of collaboration within this activity has an important influence on spectator activities at the track and how they are organized. The variety of existing information sources at the track poses not only the challenge to get information, but also to use and interpret that information to decide on how to place bets. These findings have been derived during an ethnographic study. The study, of which the design of TrottingPal is based on, has focused on understanding how spectators organize and coordinate their activities and how they exchange relevant event information. This work focuses on two dimensions; (1) the use of TrottingPal within the practices of attending spectators and (2) the usability of the design. The two field trials were focused separately on the two dimensions above. 10...