Climate Grade labels will be placed on two restaurant menus beneath all main menu items, using predetermined estimated greenhouse gas emission thresholds to assign one of five icon-plus-text labels which indicate a specific climate impact grade (A, B, C, D, and F). Thresholds are set in kgCO2e as follows: [A] <1.7, [B] >=1.7 & <2.6, [C] >=2.6 & <9.2, [D] >=9.2 & <28, [F] >=28. All labels are solid black with a white globe icon followed by white text which reads "CLIMATE GRADE". On the left side of each label, a grade is displayed, capitalized and in a white font within a solid-colored box. The color of the box corresponds with each letter grade: A = dark green, B = light green, C = yellow, D = orange, F = red. Beneath the letter grade, a gradient of all possible grades is displayed horizontally in smaller font, each grade atop a small solid box in the respective grade color. Explanatory text describing the meaning of the labels will be displayed at the top of the menu.

Participants will view two fast-food restaurant menus presented in a random order. Each menu will include main, side, dessert, and drink items, and each menu item will be displayed with an image of the item, name, price, and total calories. For main items only, Low Climate Impact labels will be displayed beneath each item. Participants will be instructed to select at least 1 and up to 4 menu items for a hypothetical meal order. Participants will be required to select a main item and, optionally, up to 3 additional items (drinks, sides, desserts).

Participants will view two fast-food restaurant menus presented in a random order. Each menu will include main, side, dessert, and drink items, and each menu item will be displayed with an image of the item, name, price, and total calories. For main items only, High Climate Impact labels will be displayed beneath select items. Participants will be instructed to select at least 1 and up to 4 menu items for a hypothetical meal order. Participants will be required to select a main item and, optionally, up to 3 additional items (drinks, sides, desserts).

Participants will view two fast-food restaurant menus presented in a random order. Each menu will include main, side, dessert, and drink items, and each menu item will be displayed with an image of the item, name, price, and total calories. For main items only, Traffic Light labels will be displayed beneath each item. Participants will be instructed to select at least 1 and up to 4 menu items for a hypothetical meal order. Participants will be required to select a main item and, optionally, up to 3 additional items (drinks, sides, desserts).

Participants will view two fast-food restaurant menus presented in a random order. Each menu will include main, side, dessert, and drink items, and each menu item will be displayed with an image of the item, name, price, and total calories. For main items only, Climate Grade labels will be displayed beneath each item. Participants will be instructed to select at least 1 and up to 4 menu items for a hypothetical meal order. Participants will be required to select a main item and, optionally, up to 3 additional items (drinks, sides, desserts).

Cumulative total kilograms of carbon equivalent (kgCO2e) per kilogram of food for all meal items. Beverages are excluded and assessed through other secondary outcomes. Beverages are excluded and assessed through secondary outcomes (#5 & #11).

Measured as a dichotomous variable (yes/no) indicating whether participants' hypothetical meal orders include an item containing red meat.

The total number of calories in participants' hypothetical meal orders, calculated as the sum of calories across all menu items selected. Higher values indicate more calories selected.

The total amount of saturated fat in participants' hypothetical meal orders, calculated as the sum of saturated fat (grams) across all menu items selected. Higher values indicate more saturated fat selected.

The total amount of sugar in participants' hypothetical meal orders, calculated as the sum of sugar (grams) across all menu items selected. Higher values indicate more sugar selected.

The total amount of protein in participants' hypothetical meal orders, calculated as the sum of protein (grams) across all menu items selected. Higher values indicate more protein selected.

The total amount of fiber in participants' hypothetical meal orders, calculated as the sum of fiber (grams) across all menu items selected. Higher values indicate more fiber selected.

The total amount of sodium in participants' hypothetical meal orders, calculated as the sum of sodium (milligrams) across all menu items selected. Higher values indicate more sodium selected.

Measured as a dichotomous variable (yes/no) indicating whether participants' hypothetical meal orders include a sugar-sweetened beverage.

This outcome will measure participants' knowledge of the relative climate impacts of meals with different main proteins. Participants are prompted to numerically rank three meals by climate impact. The exact prompt is: "Please rank the below food options from smallest (1) to largest (3) climate impact. Write "1" next to the food option with the smallest climate impact, "2" next to the option with the middle climate impact, and "3" next to the option with the largest climate impact." Each rank item reads "Meal in which the main protein is beef", "Meal in which the main protein is chicken", and "Meal in which the main protein is tofu". Responses will be analyzed by % who correctly rank the 3 items by experimental condition.

This outcome will measure participants' knowledge of the relative climate impacts of menu items by label condition. Via two questions, one per restaurant, participants are prompted to indicate "Which menu item below has a larger contribution to climate change (i.e., produces more greenhouse gas emissions)?". Three response options are provided: two images of main menu items by label condition and "The menu items have the same climate impact". Responses will be analyzed as the % who answer both questions correctly by label condition.

Measured by whether participants noticed labels on the menus, in addition to calorie labels. The exact question is, "On the menus you saw, did you notice any labels (other than calories) next to or below the menu items?" Response options are "Yes", "No", and "Don't Know".

Measured by whether participants who noticed labels, in addition to calorie labels, correctly identify the purpose of the labels. Response options are "Sugar", "Sodium", "QR code", "Climate Impact", "Organic", "Healthy", "Unhealthy", "None of these", and "I don't know/ I can't remember".

This modified 4-item UNC-PME scale measures how much the label placed beneath high climate impact menu items, discouraged consumption or evoked concern or unpleasantness about consumption of high climate impact foods. Responses to all questions will be measured on a 5-point unipolar Likert scale from 1=Not at all to 5= A great deal. The higher the score, the higher the perceived effectiveness.

Measured by the cumulative total price (USD) of participants' hypothetical meal orders per restaurant, based on the prices displayed on the survey menus.

Measured by the level of appeal attributed to 8 main menu items, 4 from each restaurant, by label condition. All items are assessed on a 7-point Likert scale with response options of "Very unappealing", "Unappealing", "Slightly unappealing", "Neither appealing nor unappealing", "Slightly appealing", "Appealing", "Very appealing" for each food item. Higher score, higher appeal.

Measured by the level of healthfulness attributed to 8 main menu items, 4 from each restaurant, by label condition. All items are assessed on a 7-point Likert scale with response options of "Very unhealthy", "Unhealthy", "Slightly unhealthy", "Neither unhealthy nor healthy", "Slightly healthy", "Healthy," "Very healthy" for each food item.

Measured by the level of climate impact attributed to 8 main menu items, 4 from each restaurant, by label condition. All items are assessed on a 7-point Likert scale with response options of "Extremely high climate impact", "Very high climate impact", "High climate impact", "Moderate climate impact", "Low climate impact", "Very low climate impact", "Extremely low climate impact" for each food item.

Measured by the level of support or opposition for policies and practices regarding food, nutrition, and consumer information. This outcome is measured across five survey items with response options of "Strongly oppose", "Oppose" Somewhat oppose", "Neither support nor oppose", "Somewhat support", "Support", "Strongly support" for each specific policy described.