Monitoring of the ripening of olives in order to decide the best harvesting period is a critical control step in extra-virgin olive oil production. The first part of this chapter presents the main phenomena of olive ripening. The second part presents the main harvesting systems: hand-held harvesting machines for traditional olive groves, trunk shakers for semi-intensive and intensive olive groves and straddle harvesters for super-intensive olive groves. Systems are compared in terms of harvesting efficiency and labour productivity. In Annex 8.1 a system of maturity assessment and harvesting decision is described in detail.