Previous research on married couples has indicated that loneliness, an unrealized desire for close relationships, can affect even partnered adults. In addition to individual perceptions of the marital relationship, partner perceptions of the relationship might also heighten married adults’ experiences of loneliness. I employed a dyadic approach derived from the emotion-in-relationships model to examine the extent to which individual and partner reports of four dimensions of relationship quality are risk factors for loneliness among married older adults. Using structural equation modeling with dyadic data from 779 opposite-sex couples in the National Social Life, Health, and Aging Project (2010–2011), I found that spouses’ reports of positive and negative relationship quality were associated with loneliness beyond individuals’ reports. For positive relationship quality, a partner’s report had an effect equal to one’s own report. For negative relationship quality, one’s own and one’s partner’s perceptions operated in opposite ways. There were no differences between husbands and wives, and neither partner’s reports of shared marital activities or sexual relationship quality were associated with loneliness. Overall, results suggest that for married older persons, dyadic approaches to therapy might most effectively alleviate loneliness.