Both 'actions' and 'interactions' can be considered as micro-operations that can be aggregated from a systemic perspective. Whereas actions operate historically, interactions provide the events retrospectively with meaning. Luhmann's sociology of communication systems adds to the approach of symbolic interactionism the question of what global dimensions of communication mean for local interactions. When communication is functionally differentiated--for example, in terms of media--tensions can be expected to develop between local organizations and global developments of communication structures. Interfaces enable us to translate selectively among (provisionally) stabilized representations, for example, in professional practices. 'Big science' and 'high tech' can be considered as organizational acculturations of an emerging level of sophistication in global communications. The global dimension remains a hypothesis, but entertaining this hypothesis of 'globalization' restructures the local expectations.