The McDonald's Happy Meal was introduced nationally in 1979.
The idea began with Yolanda Fernández de Cofiño, who ran McDonald's restaurants in Guatemala. Her child-sized “Ronald Menu” combined a small hamburger, fries, dessert, and a toy. McDonald's executive Bob Bernstein later developed the packaged meal concept, including colorful artwork, games, and a surprise gift.
The first U.S. test took place in Kansas City in October 1977, and other markets followed. McDonald's then rolled the product out nationwide in 1979, which is why 1979 is the standard answer to this question. The original Happy Meal was not limited to the familiar red box and movie toys seen today; early versions included items such as a McDoodle stencil, McWrist wallet, puzzle lock, spinning top, and character-shaped eraser.
A common mix-up is answering 1977, the year of the Kansas City test. Another is treating the toy as the invention itself: restaurants had offered children's toys before, but the Happy Meal unified the food, packaging, and toy into one branded children's meal.