This article explores the theoretical and empirical implications of incorporating forgone opportunities in strategic management research. Drawing on the well-studied literature examining whether firms should reinvest in focused businesses or pursue alternatives of diversifying and/or paying out excess cash to shareholders, hypotheses are developed for when diversification and payout policy, as the opportunity costs of reinvesting in the firm’s original businesses, will present firms with higher and lower opportunity costs. Empirical results suggest that the value of reinvestment in existing businesses is higher for firms facing lower opportunity costs of forgoing other alternatives (e.g. diversification and paying out) than for firms that have much higher opportunity costs of forgoing these same alternatives. Implications for incorporating opportunity costs into the diversification literature and the broader strategic management literature are also explored.