Bipolar I disorder (BPI) is among the top 10 most debilitating illnesses globally. In this critical review, we first review recent functional neuroimaging findings in two core domains of pathology in BPI: emotion processing and executive control. These abnormalities in core domains represent potential endophenotypes of the illness. We then show that an emerging number of studies have demonstrated that neuroimaging can help to identify endophenotypic markers whose identification would help to clarify diagnosis and discriminate the depression in BPI from that of unipolar depression and identify at-risk individuals who will subsequently develop the illness (to facilitate early intervention). We end by reviewing the new directions in neuroimaging in BPI, including studies of children with bipolar disorder, potential medication effects, and the use of newer neuroimaging techniques to help us achieve the previously mentioned goals of improving BPI patients' mental well-being.