There is a growing amount of research to suggest that even being a mere witness to an uncivil interaction can cause an individual to instigate incivility. Organisations are struggling to contain and manage incivility in the workplace, and more research is needed to investigate how these behaviours spread in the first place. The current study aimed to explore the relationship between witnessing supervisor or co-worker incivility and subsequent instigating of incivility as well as the subsequent targets of incivility, to further advance the literature on incivility spirals. 201 participants from the US completed three questionnaires over a 4-week period, which measured the three types of incivility: experiencing incivility, witnessing incivility, and instigating incivility. Regression and correlational analysis showed witnessing supervisor incivility to be more significantly related to future instigation of incivility than witnessing co-worker incivility. The results also provided further insight into the theory of incivility spirals, showing that those who witness incivility are more likely to instigate incivility toward a third-party target, than the original instigator. These findings suggest that secondary incivility spirals are more common in the workplace than primary spirals, and that supervisors’ actions are the primary source of incivility spirals. The results of the present study have important theoretical and practical implications and demonstrate the need for future research to explore witnessed incivility and its consequences further.