Treatment adherence is a frequent problem in bipolar disorder, with research showing that more than 60% of bipolar patients are at least partially nonadherent to medications. Treatment nonadherence is consistently predictive of a number of negative outcomes in bipolar samples, and the discontinuation of mood stabilizers places these patients at high risk for relapse. Several types of adjunctive treatment (family, psychoeducational, cognitive-behavioral) have been investigated for improving symptoms and functioning in bipolar patients with some success. To date, less attention has been paid to developing treatments specifically to promote treatment adherence to and engagement with pharmacological as well as behavioral treatments in patients with bipolar disorder. First, we review the effects of adjunctive interventions specifically on treatment adherence outcomes in 14 published clinical trials. Based on this empirical knowledge base, we present a preliminary description of the treatment strategies that appear most promising for improving adherence. The article also provides research recommendations for developing more effective interventions for the purpose of improving bipolar treatment adherence. Finally, special treatment considerations, including the potential impact of comorbid substance abuse and bipolar depression, are discussed.