Even in emergency situations, gender needs to be taken into account by humanitarian assistance. Taking account of gender increases the effectiveness of humanitarian assistance because it allows for a better understanding of the crisis and more appropriate responses which aim to meet the needs of both women and men. This is because women and men are affected by crises in different ways. Women may have lesser access to information or resources which means they are less able to cope. Women may be more vulnerable to sexual violence which is likely to increase in conflict or emergency situations. Men may lose self esteem not being able to support their families economically (even if they were not actually doing so before the crisis). Humanitarian assistance must take account of the differences between women and men, but can also challenge these differences. Humanitarian disasters can be an opportunity for social change around gender if women are enabled to participate in reconstruction and allowed decision making power in this. This guide presents myths and realities of gender mainstreaming in humanitarian assistance, questions to ask for reviewing proposals and reports, and checklists for the specific sectors of human rights, food and agriculture, water and sanitation, health, education and economic recovery and reconstruction.