For older and newer firms, larger and smaller, there are strengths and weaknesses related to firm age and size. What may be a strength for one type is often a weakness for another. This analysis brings together the theoretical frameworks of population and organizational ecology and strategic management to examine the liabilities of firm age and size, and strategies each type of firm may use to overcome potential liabilities. The theoretical perspectives each focus on change, but at different levels of analysis – this study seeks to include both population and organizational change. It examines characteristics of older, larger firms and newer, smaller organizations that make change difficult or that cause the firm to face a volatile environment. Strategic implications of the liabilities of age and size are discussed. For smaller firms, for example, partnerships with other organizations can provide access to resources (and stability); for larger firms, partnerships can provide access to new technologies (and revitalization).