This overview aimed to systematically synthesize evidence from existing systematic reviews to signpost practitioners to the current evidence base on nonpharmacological interventions to improve depression, anxiety, and quality of life (QoL) in people with dementia and to discuss priorities for future research. The databases MEDLINE, PsycINFO, Scopus, and Cochrane Central Register of Controlled Trials were searched in August 2017 with an updated search in January 2019. Fourteen systematic reviews of randomized controlled trials of nonpharmacological interventions were identified. Dementia stage was rated moderate or severe in the majority of the reviews and type of dementia varied. Interventions reported to be effective were cognitive stimulation (QoL: standardized mean difference [SMD] = 0.38), music-based therapeutic interventions (depression: SMD = −0.27, anxiety: SMD = −0.43, QoL: SMD = 0.32), and psychological treatments (mainly cognitive behavior therapy; depression: SMD = −0.22, anxiety: MD = −4.57). Although health-care professionals are recommended to continue using these approaches, future research needs to focus on the type and form of interventions that are most effective for different stages and types of dementia.