Background: This study examines the experiences of qualified nurses working with individuals diagnosed with both intellectual disability and personality disorder (PD) in a medium-secure forensic intellectual disability setting. Potential training needs are highlighted, as well as other ways in which services could better support staff to work effectively with this client group. Method: In-depth, semi-structured interviews were used to explore the nine participants' experiences; the narratives were analysed with interpretative phenomenological analysis (IPA). Results: Four master themes emerged from (i) disorder overriding disability; (ii) resilience; (iii) ambivalence towards label and (iv) knowledge. Conclusion: The findings highlight that for these participants, the clients' intellectual disability appeared to be lost under the complexity of the PD diagnosis. The clinical implications are discussed in terms of developing training, supervision and support.