Introduction.- Theroy and Empirics of Investment: A Selective Review of the Literature: Theories of Firm Investment and their Empirical Performance; Firm Investment Under Financial Constraints; Non-standard Constraints and Firm Behavior: A Research Program.- A Dynamic Programming Framework for the Analysis of Firm Decisions: An Introduction to Markov Decision Processes; Strategies for the Econometric Analysis of Dynamic Decision Processes; An Application: Firms'Joint Investment and Exit Decisions.- Plant-level Investment and Exit Decisions and Firm-level Financial Status: Introduction and Overview; Alternative Measures of a Firm's Financial Status; The Empirical Model of Firm Behavior Under Financial Constraints; Description of the Plant-level Dataset; A Reduced-form Model of Plant Growth and Exit; Empirical Results for the Structural Model of Investment and Exit; Summary and Discussion.- Concluding Remarks.