It has been widely reported that surveys have found high levels of ICD-11 complex post-traumatic stress disorder (CPTSD) (12.6%) among police personnel, and a further 8.0% with PTSD. Until now, there has been little research linking PTSD to working conditions. This report examines how the prevalence of CPTSD varies with measures of job quality. Positive indicators of job quality (for instance, the feeling of doing meaningful work, support from colleagues and managers, work–life balance, job security, and promotion prospects) typically predict half the rate of CPTSD. Negative indicators of poor job quality (such as having to deal with sexual harassment or extreme time pressures) are associated with CPTSD rates twice as high as the policing average. Additional evidence shows that police forces with better working conditions tend to have markedly lower rates of PTSD. These analyses cannot prove the direct causal relationship from job quality to PTSD but do provide unequivocal evidence of an association. Improving job quality may greatly reduce the level of this most debilitating psychological disorder, CPTSD, in the policing population.