Sense of coherence (SOC) is the fundamental concept of the salutogenic approach to health promotion. The main aim of the current longitudinal study is to consider whether SOC has had a positive effect in reducing people's levels of stress during the prolonged time of the pandemic or rather stress has posed a threat to SOC. A large sample of Italian adults completed an online questionnaire at three different moments of the Covid-19 pandemic (from March 2020 to May 2021). To test the reciprocal associations between SOC and stress we estimated a cross-lagged panel model. Results questioned the stability of SOC, which changed across the different moments of the pandemic, and its causal role with respect to stress since, after controlling for gender and age, it emerged a significant effect only from stress to SOC. The implications of these results and the further expansions of the study are discussed.