Innovation project portfolios as organizations’ strategic investments face uncertainties both within the organization and in the business context. Management of such uncertainties is distributed in the organizations and requires cooperation, but it may be challenging to coordinate in and across the complex portfolios. This study increases knowledge of the social aspects of innovation project portfolio uncertainty management, when its responsibilities are divided across managerial levels and steering committees. Experiences in two highly innovative case firms reveals firm-specific emphases in the attention to uncertainties, potentially stemming from industry dynamics. Complex mechanisms are used for filtering uncertainty information from individual actors’ sensing and seizing activities to steering committees’ decision-making processes, across the levels of projects, programs, portfolios, and strategic management. Peer reviewed