The Infrequency-Posttraumatic Stress Disorder scale (Fptsd), recently created for the Minnesota Multiphasic Personality Inventory-2 (MMPI-2), has demonstrated incremental validity over other MMPI-2 scales in malingered posttraumatic stress disorder (PTSD) detection. Fptsd was developed with combat-exposed PTSD patients, potentially limiting its use with PTSD patients in general. The current study evaluated the MMPI-2's F, Infrequency-Psychopathology scale (Fp), and Fptsd scales in discriminating genuine civilian PTSD among 41 adult victims of child sexual abuse from a group of 39 students instructed to simulate PTSD. Analyses demonstrated Fptsd's incremental validity over F but not over Fp. Based on the two studies examining Fptsd, Fptsd may be more appropriate for combat trauma victims, and Fp may be more appropriate for civilian trauma victims.