AbstractThe study of subjective well-being (SWB) is important as it is related to the reduction of morbidity and mortality, with the maintenance of functionality and autonomy in the elderly population. The impact of the formative intervention on the SWB of informal caregivers (ICGs) during the pandemic crisis of COVID-19 was analyzed. This study is a quasi-experimental single-group, longitudinal study with a sample of 31 ICGs and their dependents. A form was used for data collection, and data processing was performed using IBM SPSS (Statistical Package for the Social Sciences), using descriptive statistics and inferential statistics. Of the total sample, the majority were female (90.3%). The difference between the mean of positive affection and negative affection at Moment 1 (M1) was –0.0581 ± 0.71590 and 0.04645 ± 0.53326 at Moment 2 (M2). The mean rank ordering of the difference between the two types of affection differed significantly between M2 and M1 (Wilcoxon:p< 0.000), with that of M2 being higher than M1 (16.93 > 2.50). The formative intervention, within the scope of community nursing, had a significant impact on increasing the SWB of the ICG in this sample. This study may contribute to improving the SWB of ICG and their dependents.