Selective availability in instant messaging can improve connectiveness while at the same time keeping disruption low. In this paper we report on an experience sampling study of selective availability in instant messaging to inform the design of lightweight mechanisms with little user effort. Author Keywords Computer-Supported Cooperative Work; ComputerMediated Communication; Instant Messaging. ACM Classification Keywords H.5.2 [Information Interfaces and Presentation]: User Interfaces — Graphical User Interfaces, User-Centred Design; H.5.3 [Information Interfaces and Presentation]: Group and Organisation Interfaces — Computer-Supported Cooperative Work. General Terms Human Factors.