The reported study was conducted to develop a reliable and valid scale to measure the construct of trust in advertising. A multi-stage research project was conducted: (1) general consumer and advertising expert interviews were conducted to identify initial items; (2) a survey of 260 college students was executed to assess reliability of the scale; (3) a survey of 259 non-student adults was performed to test the reliability and validity of the scale; and (4) the development of a 20-item Likert format scale (the ADTRUST scale) to capture and measure the concept of trust in advertising. The ADTRUST scale showed high reliability and demonstrated concurrent, convergent, discriminant, and nomological validity. The research found that trust in advertising is a multi-dimensional construct with four distinct components: Reliability, Usefulness, Affect, and Willingness to Rely On. Thus, the construct of trust in advertising should be operationalized as the combination of (a) consumer perception of reliability and usefulness of advertising, (b) consumer affect toward advertising, and (c) consumer willingness to rely on advertising. The ADTRUST scale proved itself to be a valid measure of trust in advertising in the context of two different media: broadcast media and print media. Consumer trust in advertising,measured with the ADTRUST scale, varies across specific advertising media types. Five ad-media were examined: television, newspapers, radio, magazines, and the Internet. The results of ANOVA indicate that trust in advertising is significantly lower for Internet advertising than for the other media types. Across all five media investigated, media credibility was consistently associated with media-specific ad-trust, indicating that trust in a medium and trust in advertising in that medium are directly related. The significance of the results is discussed in relation to the research literature. Implications of the findings are discussed and limitations and suggestions for future research are presented. Index words: Trust, Advertising, Scale Development