This article takes stock of the growing field of online deliberation research. Our review of the theoretical and empirical findings is guided by a framework encompassing the three relevant components of deliberation: the institutional design that enables and fosters deliberation (institutional input: “design”), the quality of the communication process (communicative throughput: “process”), and the expected results of deliberation (productive outcome: “results”). Our findings show that scholarly attention is unevenly distributed across the different components of the framework. Most research has focused on the quality of the online discussion (process). A fair amount of research has focused on the institutional conditions fostering deliberation (design), while the outcomes of online deliberation processes (results) have mostly been neglected. This picture is repeated in terms of the causal relations between design, process, and results of deliberation: Most studies have dealt with the effects of the platform design on the degree of deliberation (design-process). Much less is known about how the process of deliberation shapes the outcomes of deliberation (process-results). Studies investigating all three aspects of deliberation and their causal links (design-process-results) are particularly rare.