On-again/off-again relationships challenge the standard dichotomous definition of relationship stability (i.e., whether the relationship remains intact or dissolves). This chapter reviews the various conceptualizations of stability. Although on-off partners report less relationship stability when using subjective, one-time assessments (e.g., perceived stability, sense of security, or persistence in the relationship), a process-oriented assessment of stability is advocated in which relationship dynamics are measured over time. As argued by chaos theory, fluctuations over time could indicate a stable pattern. For example, research suggests certain fluctuations are associated with greater stability in on-off relationships. A process-oriented perspective could thus provide a more nuanced assessment of relationship stability for both on-off and non-cyclical relationships. Additional considerations for future research are also offered.