||The aim of the study was to develop an empirical measure for everyday information mastering (EIM). EIM describes the ways that individuals, based on their beliefs, attitudes, and expectations, orient themselves to information as a resource of everyday action. The key features of EIM were identified by conceptual analysis focusing on three EIM frameworks. Four modes of EIM—Proactive, Social, Reactive, and Passive—and their 12 constituents were identified. A survey of 39 items was developed in two pilot studies to operationalize the identified modes as measurable EIM constituents. The respondents in the main study were upper secondary school students (n = 412). Exploratory factor analysis (EFA) was applied to validate subscales for each EIM constituent. Seven subscales emerged: Inquiring and Scanning in the Proactive mode, Social media-centered, and Experiential in the Social mode, and Information poor, Overwhelmed, and Blunting in the Passive mode. Two constituents, Serendipitous and Intuitive, were not supported in the EFA. The findings highlight that the core constituents of an individual's everyday information mastering can be operationalized as psychometric scales. The instrument contributes
to the systematic empirical study of EIM constituents and their relationships. The study further sheds light on key modes of EIM.