Background: Nigerian policymakers are debating task-shifting injectable contraceptive services to Patent and Proprietary Medicine Vendors (PPMVs). Methodology: One hundred fifty-two PPMVs were trained to provide injectable contraceptives in Oyo and Nasarawa states. Data were collected before and 1, 3 and 9 months post-training. χ2 tests were conducted to assess associations between survey time points. Main findings: Few PPMVs had the necessary knowledge to provide injectables pretraining. A majority demonstrated increased knowledge after the training. Knowledge required for screening and counseling clients was lower than knowledge on administration. Conclusion: PPMVs should be trained before providing injectable services. Additional research is needed on the benefits of job aids for screening and counseling.