No, baking powder is not strictly required in all cookies. Many cookies work perfectly well without it, though it serves a specific purpose when included. Baking powder is a leavening agent that helps cookies rise slightly and creates a lighter, airier crumb structure. Cookies without baking powder tend to be denser and chewier, which is actually desirable for many varieties like chocolate chip, shortbread, or sugar cookies. If a recipe calls for baking powder and you want to omit it, the cookies will simply be thicker and less puffy. Alternatively, you can use other leavening agents like baking soda (which requires an acidic ingredient like buttermilk or brown sugar to activate) or skip leavening entirely. Some cookies intentionally contain no leavening agent at all—brownies, for example, often rely on eggs and fat for structure rather than chemical leavening. The choice depends on your desired texture: baking powder creates lift and tenderness, while its absence produces denser, chewier results. If you're substituting or omitting baking powder, you may need to adjust other ingredients or expect slightly different texture and thickness in the final product.