Objectives: This systematic review and meta-analysis assesses the effectiveness of psychological interventions that involve people with dementia or mild cognitive impairment (MCI) and their informal caregivers, and target improvements in the management of the behavioral and psychological symptoms of dementia (BPSD); quality of life; and/or burden reduction for people with either dementia or MCI and their informal caregivers. Methods: Studies were identified through database searches (Cochrane Library, CENTRAL, CINAHL, EMBASE, MEDLINE and PsychINFO) and clinical trials registers (ClinicalTrials.gov and ). Data were pooled for meta-analysis. Results: Database and reference list searches identified 1,878 references, of which fourteen studies were included. Positive effects were found on the anxiety symptoms of people with dementia on the RAID scale; on the quality of life of people with dementia on the self-rated QoL-AD scale; and on informal caregiver burden on the Zarit Burden Interview. Conclusions: Psychological interventions involving whole dyads have some promise for both people with dementia and informal caregivers, but are still far from uniformly effective across BPSD, quality of life, and caregiver burden. Further research directions are discussed.