Relationship quality refers to the perceived quality of a close relationship (i.e., romantic relationship, friendship, or family).

Relationship quality (sometimes used interchangeably with relationship satisfaction, relationship flourishing, or relationship happiness), in the context of close interpersonal relationships is generally defined as a reflection of a couple's overall feelings towards their relationship. More simply, it is the extent to which members in a relationship (romantic or otherwise) view their relationship as positive or negative.

The determinant of relationship quality is often a variety of self-reported evaluations of traits that make up relationship quality. For instance, feelings of closeness may be measured via questions that ask an individual to rate the extent to which they identify with statements. I.e., "I feel close to my partner", "I am comfortable sharing personal thoughts and feelings with my partner", etc. These questions are typically asked on a Likert scale and the average of those scores represents an individual's feelings of closeness toward their partner. Some scales are considered unidimensional and attempt to directly measure the construct of relationship quality. Other scales, considered multidimensional, repeat this process for other hypothesized components (e.g., closeness and satisfaction) before aggregating dimensions into a representative "relationship quality" score.

Historically, relationship quality has been the most commonly studied in the context of intimate romantic relationships. More recently, the study of relationship quality has extended to include other types of close relationships (see: friendships, family, sibling, parent). There is not always agreement among scholars about what domains should be included in the measurement of relationship quality, even within the different types of close relationships. Despite this, relationship quality and its predictors have been of popular interest to relationship scholars due to the range of psychological and relational outcomes that high quality relationships have been positively linked and associated with.

Most early literature attempted to measure romantic relationship quality by centering around two approaches. While both used self-reports of how individuals perceived their relationships, the first attempted to quantify observable behaviors of relationship quality (e.g., frequency of conflict, engagement in relationship maintenance behaviors, time spent together) while the second focused on assessing internal perceptions of the relationship (e.g., perceived feelings of commitment, passion, or trust). Today, many scales measuring relationship quality focus on the second approach, attempting to identify different psychological 'domains', 'dimensions', or 'constructs' that represent relationship quality as a whole when combined.

Though there is differing agreement among scholars, some of the common dimensions thought to underlie relationship quality include: satisfaction, commitment, trust, closeness, intimacy, passion, independence, and relationship flourishing.

Some of the psychometric scales most commonly used by scholars to measure relationship quality in romantic couples include:

A substantive body of work has focused on the importance of high quality romantic relationships being linked to physical and physiological health outcomes. Those in high quality relationships are less likely to be diagnosed with or symptomatic for generalized anxiety disorder, post-traumatic stress disorder, major depressive disorder, or bipolar disorder. Those who perceive their relationship as being higher quality are typically happier, less stressed, and more satisfied with life when compared to those in low quality relationships. Relationships have also been consistently shown to contribute strongly to physical health with higher relationship quality in couples being associated with positive outcomes ranging from increased self-reported health ratings to decreased mortality, increased cardiovascular functioning, and increased wound healing rates.