Personality influences on social relationships and vice versa were lon
gitudinally studied. Personality affected relationships, but not vice
versa. After entry to university, 132 students participated for 18 mon
th in a study in which the Big Five factors of personality, the subfac
tors Sociability and Shyness, and all significant social relationships
were repeatedly assessed. A subsample kept diaries of all significant
social interactions. After the initial correlation between personalit
y and relationship quality was controlled for, Extraversion and its su
bfactors, Agreeableness, and Conscientiousness predicted aspects of re
lationships such as number of peer relationships, conflict with peers,
and falling in love. In contrast, relationship qualities did not pred
ict personality traits, and changes in relationship qualities were unr
elated to changes in personality traits. Consequences for dynamic-inte
ractionistic views of personality and relationships are discussed.