Core and infrastructure business activities are vital to the organization, and are growing more and more dependent on information systems. Theory suggests that more core and infrastructure business activities would inspire more strategic information systems planning which in turn would result in greater planning effectiveness. One hundred thirty chief information officers in manufacturing companies completed a questionnaire about the extent that their organization performed core and infrastructure business activities, and carried out technical, personnel, and procedures planning. The findings showed that infra-structure activities lead to all three types of planning whereas core activities lead only to procedures planning. Moreover, they showed that technical planning leads to planning effectiveness whereas personnel and procedures planning do not. The findings suggest that future researchers might try to uncover the reasons that core activities do not lead to more information systems planning. For practitioners, the findings suggest that managers reconsider how their organizations respond to core and infrastructure needs, and whether they should adjust their information systems planning.