Vanishing Viper 2019’ was organised in the wake of continuing evidence for declines in British populations of the northern viper or adder (Vipera berus).  The meeting included participants from other European countries, whose insights suggest that the drivers of adder declines in mainland Europe are similar to those in Britain.  Consequently, we stand to benefit from their knowledge and experience.  It was concluded that if adder declines continue at the present pace, then Britain may be left with a few large, flourishing populations, but that many of the smaller populations will be lost as appears to have happened in Belgium, France, Germany and The Netherlands.  The meeting considered a range of conservation actions including improvements to habitat management, the creation of adder ‘ARKs’, population restoration by genetic or demographic enhancements, community level promotion and outreach, and opportunities for new policy-driven environmental schemes.