The present invention relates to a washing machine and a method of controlling a washing machine. According to the washing machine and the method of controlling the washing machine in accordance with the present invention, the drum is operated at a first speed so that laundry tumbles within the drum. A laundry amount within the drum during the first speed operation is sensed. The drum is driven at a second speed so that part of the laundry tumbles within the drum and another part of the laundry adheres to the drum. Operation commands for driving the drum subsequent to the first speed operation are changed based on the sensed laundry amount. Accordingly, at the time of a dehydration cycle, stability of the washing machine and laundry balancing can be ensured.