Analysts who conduct trauma-focused treatments have much to learn from Wilfred Bion's contributions to the understanding and treatment of PTSD. Concepts such as catastrophe and catastrophic change can illuminate the subjective experience of PTSD patients, the beta screen concept sheds light on dissociative phenomena, and, as shown in a clinical vignette, the analyst can use his alpha function to transform the patient's fragmented raw material into alpha elements. A second clinical vignette shows how during a cognitive intervention the analyst can impart this alpha function to the patient and use his reverie to help the patient assimilate previously intolerable fragments into a coherent narrative. Finally, the idea of knowing mental pain (Bion's K) is discussed in relation to the processing of traumatic memories.