The purpose of this study was to explore the relationship between the structure of the family of origin and tendency to forgive by investigating attachment as a potential mediating variable. Polish version of the FACES-IV (Olson & Gorall, 2003; Margasiński, 2015); the Heartland Forgiveness Scale (Thompson et al., 2005; Kaleta, Mróz, & Guzewicz, 2016), the Revised Adult Attachment Scale (Collins & Read, 1990; Collins, 1995/2008; Adamczyk, 2012) were used. The sample consisted of 91 individuals aged 19–26 (58.25% females). The results showed that maladaptive family of origin structures are associated with a lower level of dispositional forgiveness. However, no statistically significant relationship was found between adaptive family of origin structures and dispositional forgiveness. Furthermore, the results indicate that insecure attachment is a mediator in the relationship between the maladaptive family of origin structure and dispositional forgiveness.