Memory is essential to adaptive behavior because it allows past experience to guide choices. Emerging findings indicate that the neurotransmitter dopamine, which signals motivationally important events, also modulates the hippocampus, a crucial brain system for long-term memory. Here we review recent evidence that highlights multiple mechanisms whereby dopamine biases memory towards events that are of motivational significance. These effects take place over a variety of timescales, permitting both expectations and outcomes to influence memory. Thus, dopamine ensures that memories are relevant and accessible for future adaptive behavior, a concept we refer to as 'adaptive memory'. Understanding adaptive memory at biological and psychological levels helps to resolve a fundamental challenge in memory research: explaining what is remembered, and why.