Two studies report the development and validation of the Humor At Work (HAW) questionnaire, developed specifically for the measurement of humor within workplace settings. Using an empirical approach to item selection, 150 items were administered over the internet to an international (largely Australian) sample of 339 individuals in a range of occupations. Exploratory factor analysis produced an initial questionnaire comprising eight scales. Study 2 administered the questionnaire, and several other self-report instruments, to a second sample of 377 working Australians. The eight confirmed scales were validated. Also using confirmatory factor analysis, the initial questionnaire was reduced to a final 13-item instrument comprising two scales: Pleasant Climate and Unpleasant Climate. These scales were independent of age, gender, education, and position. They were also independent of the factors of the Big Five, mood measures of positive and negative affect, social desirability, and altruism. Since Unpleasant Climate was positively correlated with the Climate of Fear measure of Ashkanasy and Nicholson (2003), and Pleasant Climate with the Affiliative and Self-Enhancing humor styles from Martin et al.'s (2003) Humor Styles Questionnaire, the HAW provides a useful measure of humor within the workplace environment.