Background and objectives: This study aimed to determine the frailty, prognosis, complexity, and palliative care complexity of nursing home residents with palliative care needs and define the characteristics of the cases eligible for receiving advanced palliative care according to the resources available at each nursing home. Materials and Methods: In this multi-centre, descriptive, and cross-sectional study, trained nurses from eight nursing homes in southern Spain selected 149 residents with palliative care needs. The following instruments were used: the Frail-VIG index, the case complexity index (CCI), the Diagnostic Instrument of Complexity in Palliative Care (IDC-Pal), the palliative prognosis index, the Barthel index (dependency), Pfeiffer's test (cognitive impairment), and the Charlson comorbidity index. A consensus was reached on the complexity criteria of the Diagnostic Instrument of Complexity in Palliative Care that could be addressed in the nursing home (no priority) and those that required a one-off (priority 2) or full (priority 1) intervention of advanced palliative care resources. Non-parametric tests were used to compare non-priority patients and patients with some kind of priority. Results: A high percentage of residents presented frailty (80.6%), clinical complexity (80.5%), and palliative care complexity (65.8%). A lower percentage of residents had a poor prognosis (10.1%) and an extremely poor prognosis (2%). Twelve priority 1 and 14 priority 2 elements were identified as not matching the palliative care complexity elements that had been previously identified. Of the studied cases, 20.1% had priority 1 status and 38.3% had priority 2 status. Residents with some kind of priority had greater levels of dependency (p < 0.001), cognitive impairment (p < 0.001), and poorer prognoses (p < 0.001). Priority 1 patients exhibited higher rates of refractory delirium (p = 0.003), skin ulcers (p = 0.041), and dyspnoea (p = 0.020). Conclusions: The results indicate that there are high levels of frailty, clinical complexity, and palliative care complexity in nursing homes. The resources available at each nursing home must be considered to determine when advanced palliative care resources are required.