<p>In addition to replicating examinations of gender bias in the diagnosis of all cluster B personality disorders (PDs), this is the first study to examine the extent to which patient sexual orientation biases the diagnosis of antisocial, histrionic, and narcissistic PDs as well as whether or not such sexual orientation bias differs by patient gender. Furthermore, this study is the first to examine how such gender and sexual orientation biases are moderated by (1) the model of personality pathology used (i.e., traditional DSM vs. dimensional Alternate Model of Personality Disorders [AMPD]) and (2) measurement specificity (i.e., global PD measurement vs. symptom-level measurement). To undertake these examinations, it utilized a vignette describing a patient whose gender identification (man or woman) and sexual orientation (heterosexual or gay/lesbian) were experimentally manipulated. Clinicians (<em>N</em>=435) were randomly assigned to examine one of the resultant four vignettes, after which they each completed three measures of personality pathology. Though there was evidence of gender bias, such bias was twice-to-four times as weak as gender bias found in past similar studies. There was no evidence of significant diagnostic bias based on patient sexual orientation and sexual orientation bias did not differ by patient gender. Broadly, neither gender nor sexual orientation bias was moderated by the model of personality pathology underlying the measures used, by the specificity with which the pathology was measured, or by clinician characteristics (i.e., age, gender, sexual orientation, licensure status, race). Results suggest a decrease in gender and sexual orientation bias within experimental contexts relative to that which was found by prior studies. Further examinations should elucidate the mechanisms moderating diagnostic bias. </p>