Abstract: Despite high interest in native advertising, the definition and effectiveness of native advertising remain subjects of debate. To address this problem, we explored the nature of perceived advertising nativeness as experienced by media users, developed a scale to measure this perception, and examined how it influence advertising outcomes. Using survey data about 32 ad stimuli from three studies, we examined the nature and role of perceived advertising nativeness. The 6-item ad nativeness scale, consisting of two congruence dimensions (i.e., content nativeness and design nativeness), was reliable and valid, and the construct significantly influenced attitude toward the advertisement (Aad), attitude toward the brand (Ab), and purchase intention (PI). Content and design nativeness had different effects on these advertising outcomes at different levels (high vs. low) of consumer involvement. This study contributes to the theoretical knowledge of native advertising and offers an empirical method for optimizing the performance of native advertising.