xx Introduction
in new life tasks, and the ways that people’s personalities and friendships mutually
influence one another. Adams, Hahmann, and Blieszner emphasize a dynamic theo-
retical framework to describe friendships among older adults, whereby individual
behavioral, cognitive, and affective characteristics shape friendship patterns that are
embedded in a structural, cultural, temporal, and spatial context.
Part II explores whom we form friendships with. Monsour provides a cutting-
edge approach to thinking regarding the long- standing research and theory on
cross- sex and same- sex friendships by noting how an overreliance on binary con-
ceptualizations of gender and biological sex is arbitrary and limiting. Rose and
Hospital follow by reviewing research concerning facilitators of and barriers to
friendship across differences of race, ethnicity, and sexual orientation. Ledbetter
contributes a timely summary of how the emergence of social media not only has
altered conceptualizations of friendship but also may reconfigure friendship net-
works and impact the well- being of users. VanderDrift, Agnew, and Besikci describe
the ways that friendship within romantic relationships can enhance their quality and
how individuals with varying attachment styles, patterns of interdependence, and
culture may value and benefit from this differently. In another such dual- function
interaction, Morrison and Cooper- Thomas relay the complexities of friendships in
the workplace, which can vary from casual to very close, and the costs and benefits
of managing and maintaining them. Similarly, Lunsford describes how mentorship,
an instrumental relationship with an inherent power distance between roles, may
evolve into friendship, or provide aspects of friendship while still representing a
powerful association distinct from friendship. McConnell, Lloyd, and Buchanan’s
contribution suggests that, despite the fact that our relationships with pets necessar-
ily involve much projection and anthropomorphizing, human– animal interactions
represent an important social psychological model that informs us about human
expectations, beliefs about theory of mind, and needs for social belongingness.
Friendships and the relationships that include them can sour and end, and this
darker side is the purview of Part III. Clark, Fernandez, Harris, Hasan, and Votaw
focus on factors that determine the characteristics of friendships in pairs of people
who were formerly married or dating, noting the influence of such things as the
social network that the pair is embedded in, individual differences in such things
as attachment and feelings of goodwill, and situational factors such as the presence
of children or new romantic partners. Relatedly, Hojjat, Boon, and Lozano explore
the important topic of the ways in which our friends, whom we often depend on
and deeply trust, can yet visit offense, harm, and betrayal on us, and how aspects of
the transgression, the individuals involved, or the friendship determine forgiveness
versus revenge outcomes. Hibbard and Walton suggest that competition and rivalry
can be healthy and fulfilling in many sporting, social, and professional contexts,
and can be important throughout the life span, but its aggressive and unempathetic
nature can also threaten the quality of friendships.