["(1) To compare affective changes over drinking and non-drinking days among frequent drinkers and (2) to evaluate whether drinkers' expectations influence affective changes and perceived pleasure and relief from drinking.", 'Observational study involving ecological momentary assessments collected via electronic diaries during the course of 3\u2009weeks.', "Drinkers' usual settings in Columbia, MO, USA.", 'A total of 400 adult, frequent drinkers, aged 18-70\u2009years.', 'Ecological assessments included morning reports, pre-drinking random prompts, user-initiated first-drink reports and device-prompted follow-ups over drinking episodes. Participants rated positive (enthusiastic, excited, happy) and negative (distressed, sad) affect and perceived pleasure and relief from drinking in real time. A self-report questionnaire completed at baseline evaluated expectancies for enhanced sociability and tension reduction from drinking.', 'Relative to affective changes over non-drinking days, positive affect increased prior to drinking [95% confidence interval (CI)\u2009=\u20090.004, 0.023], and at first drink (95% CI\u2009=\u20090.238, 0.317), whereas negative affect decreased prior to drinking (95% CI\u2009=\u2009- 0.007, 0.000) and at first drink (95% CI\u2009=\u2009- 0.154, - 0.098). Sociability expectancies augmented increases in positive affect prior to drinking (95% CI\u2009=\u20090.009, 0.027) and at first drink (95% CI\u2009=\u20090.017, 0.169). Sociability expectancies also enhanced perceived pleasure from first drinks (95% CI\u2009=\u20090.046, 0.318). Tension-reduction expectancies attenuated decreases in negative affect at first drink (95% CI\u2009=\u2009- 0.133, - 0.029), but augmented perceived relief from first drinks (95% CI\u2009=\u20090.001, 0.304).'] Do ecological evidence that affect and perceptions of drink effects depend on alcohol expectancies?