This study examined the accuracy of measuring happiness by a single item (Do you feel happy in general?) answered on an 11-point scale (0–10). Its temporal stability was 0.86. The correlations between the single item and both the Oxford Happiness Inventory (OHI; Argyle, Martin, & Lu, 1995; Hills & Argyle, 1998) and the Satisfaction with Life Scale (Diener, Emmons, Larsen, & Griffin, 1985; Pavot & Diener, 1993) were highly significant and positive, denoting good concurrent validity. Moreover, the single item had a good convergent validity because it was highly and positively correlated with optimism, hope, self-esteem, positive affect, extraversion, and self-ratings of both physical and mental health. Furthermore, the divergent validity of the single item has been adequately demonstrated through its significant and negative correlations with anxiety, pessimism, negative affect, and insomnia. It was concluded that measuring happiness by a single item is reliable, valid, and viable in community surveys as well as in cross-cultural comparisons.