OBJECTIVE Summary estimates indicate that bystander cardiopulmonary resuscitation (CPR) can improve the chances of out-of-hospital cardiac arrest survival two-fold to three-fold. And yet, only a minority of arrest victims receive bystander CPR. This summary will review the challenges and approaches to achieve early and effective bystander CPR. RESULTS Given the host of barriers, a successful strategy to improve bystander CPR must enable more timely and comprehensive arrest identification, encourage and empower bystanders to act, and help assure effective CPR. Arrest identification can be simplified so that bystanders should start CPR when a person is unconscious and not breathing normally. Evidence from observational studies and interventional trials supports the effectiveness of chest compression-only CPR for bystanders. As a consequence, the emphasis of bystander CPR training has been modified to feature and assure chest compressions. Bystanders should initiate CPR with compressions and consider the addition of rescue breathing based on their CPR training and skills as well as special circumstances of the victim. Bystander CPR training has evolved to incorporate this emphasis. Although general community-level CPR training remains a cornerstone strategy, training directed to those most likely to witness an arrest also has a useful role. In particular, 'just-in-time' dispatcher-assisted CPR instruction can increase bystander CPR and improve the likelihood of survival. CONCLUSIONS Recent developments in bystander CPR have simplified arrest recognition and improved CPR training, while retaining CPR effectiveness. The goal of these developments is to increase and improve bystander CPR and in turn improve resuscitation.