Firms led by older CEOs invest less, but the mechanism behind this age–investment gradient remains unclear. We study how CEO age shapes investment evaluation by eliciting CEOs’ ratings of a project’s investment attractiveness in a large-scale scenario-based experiment with more than 3,700 CEOs from owner-managed Danish firms. Our design provides direct evidence on CEOs’ investment decision rules by separating baseline action propensity from sensitivity to risk moments and payout horizon. Each CEO evaluates randomized capital-budgeting scenarios relative to the status quo, allowing us to distinguish a baseline shift in willingness to view projects as compelling from age differences in responsiveness to risk characteristics and payout horizon. We document a pronounced negative age gradient in investment attractiveness that steepens around age 60. Holding expected IRR, variance, skewness, and payout horizon constant, CEOs aged 60 or older rate the same opportunities as less attractive, while age differences in sensitivity to these attributes are weak. Standard stated risk attitudes and an incentivized lottery measure show no systematic age pattern. For external validity, we construct a CEO-specific inaction propensity from the experiment—the residual tendency to rate otherwise identical projects as less attractive—and show that it predicts lower investment in administrative data. Including this measure attenuates the reduced-form age–investment association, consistent with age-related investment declines operating partly through a higher threshold for initiating action rather than broad shifts in conventional risk preferences or horizon sensitivity.