In the wake of the methodological developments that aim to render qualitative comparative analysis (QCA) "time sensitive", I propose a new procedure for carrying out QCA longitudinally. More specifically, I show first why longitudinal case disaggregation should be carried out with change-based intervals (CBIs) rather than with fixed intervals. Second, I develop a flexible lag condition (FLC) that (i) resolves two types of temporal contradictions and outcome redundancies that can result from temporal case disaggregation and (ii) allows to measure the average duration it takes for a combination of conditions to translate to an outcome. Since temporal contradictions and outcome redundancies are most likely with an increasing number of time points and conditions, as well as with CBIs in general, the FLC procedure is most useful in these cases. The fact that the interest of longitudinal analyses increases with the number of disaggregated cases underlines the usefulness of the proposed methodological innovation. Despite its suitability for mid-n and large-n analyses, longitudinal QCA with an FLC preserves a strong case-oriented and qualitative perspective and remains thereby loyal to QCA's original foundations.