This trial tests the hypothesis that increasing nonverbal affection in romantic relationships will improve blood lipid parameters (total cholesterol, high and low density lipoproteins, triglycerides), blood glucose, and immune parameters (C-reactive protein and antibodies to latent Epstein-Barr virus). 52 healthy cohabiting romantic couples took part. In half of the couples, one partner increased the frequency of romantic kissing with the other partner during the six-week trial. The other couples received no such instruction. Blood tests performed before and after the trial were used to assess the health outcomes.