Organizational commitment, senior management involvement, and team involvement are typically expected to have a positive impact on the achievement of strategic information systems planning (SISP) objectives. That is, more commitment and involvement should produce greater success. However, they might also have a quadratic impact, specifically an inverted-U relationship such that after they reach an optimum, the achievement of the objectives diminishes.A postal survey about planning practices and objectives produced usable data from 105 corporate information systems planners. Senior management involvement predicted the achievement of the objectives in a positive manner whereas organizational commitment predicted it in an inverted-U relationship. Future research should look more closely at these relationships. Planners should be more aware of the possibly detrimental effects of excessive planning.