The development of an adequate assessment instrument is a necessary prerequisite for social psychological research on loneliness. Two studies provide methodological refinement in the measurement of loneliness. Study 1 presents a revised version of the self-report UCLA (University of California, Los Angeles) Loneliness Scale, designed to counter the possible effects of response bias in the original scale, and reports concurrent validity evidence for the revised measure. Study 2 demonstrates that although loneliness is correlated with measures of negative affect, social risk taking, and affiliative tendencies, it is nonetheless a distinct psychological experience.