Finance scholars' approach to capital-structure issues reflects a progression of thought over time. This note provides an overview of the current state of capital-structure theory. One perspective on capital-structure choice is to view it as posing trade-offs among five elements: (1) the tax benefits of financing, (2) the explicit costs of financial distress, (3) the agency costs of debt (including an array of indirect costs linked to financial distress), (4) the agency costs of equity, and (5) the signaling effect of security issuance. The first two elements reflect the "modern, traditional" balancing theory of capital structure. The third and fourth build on agency theory and imperfect information and emphasize the individual incentives of decision makers. The fifth element recognizes that the very act of issuing a security can convey new information to investors when there is imperfect information. While newer theories provide a rich array of insights into aspects of financial policy beyond how much debt the firm should undertake, the downside is that at present there is no overarching synthesis of these theories. As a result, practical application requires careful identification of how these particular theories are relevant to the business, the markets, and the situation at hand. This note is well suited to an advanced corporate-finance course after students have been exposed to the basic theory.