This article presents the results of a systematic review of the literature on dialogue-based CALL, resulting in a conceptual framework for research on the matter. Applications allowing a learner to have a conversation in a foreign language with a computer have been studied from various perspectives and under different names (dialogue systems, conversational agents, chatbots…). Considering the fragmentation of what we identify under the term dialogue-based CALL, we attempt to offer a structured overview of these efforts into a conceptual framework. Through a methodical search strategy, we collected a corpus of 343 publications. From this corpus, we formalized an operational definition of dialogue-based CALL, which allowed us to identify 96 relevant systems. Analysing the type of dialogue they offer, on a continuum of constraints on form and meaning, we propose to classify those systems into four groups. We have called these branching, form-focused, goal-oriented and reactive systems, and we describe their corresponding interactional, instructional and technological traits. We summarize the main results from empirical studies on such systems, distinguishing observational, survey and experimental studies, and discuss the impact of dialogue-based CALL on motivation and L2 development, identifying positive evidence on both outcomes. Finally, we propose two main avenues for future research: relative effectiveness of dialogue-based CALL approaches, and dialogue systems as an environment for testing SLA hypotheses.