I thought I had come across this one via Prep at some point, but I can't find the link, so I figured I'd post it here! This comes from a .pdf by Sherry Ramsey.   It may prove especially helpful to writers whose settings have significant differences from Earth. It brings up some great questions and is a good way to has details out about your world.

Fundamentals
         Story Title:
         World Name:
         It is: Earth (Past/Present/Future) | | Earth, alternate history | |
Earthlike | | Not Earthlike | |

How is it the same as/different from Earth?
         Physical (size, gravity, atmosphere, weather, moon(s), sun, constellations, etc.)
         Historical (wars, myths, legends, political events, treaties, spaceflight, etc.)

People
         What races inhabit the world? In what ratios?
         What is the population of: the world ________ the country ________
cities ________ towns ________ villages ________
         What languages are spoken?
         Do the races have specific cultural and customary rituals? How important are
they? What else is notable about the races?
         What other creatures inhabit the world? Any intelligent ones?

Technology
         What level of technology exists on this world?
         Is is the same globally, or does it differ? Is it distributed by racial or economic factors? Does this have impact on the story?
         Is there a technological aspect that has significant impact or importance in the story?

Magic/Supernatural
         Is there magic or other supernatural in this world? More than one type?
         How does magic work?
         What are the limits of magic? What magic taboos exist?

Geographical
         What are the major geographical features?
         What natural resources exist? How are they utilized?
         What are the seasons?
         What are the most common forms of transportation?

Geopolitical
         Is world history important to the story? In what ways?
         What is the political system (or systems) of the various or relevant countries?
         How are relations between countries? Are any currently at war?

Society
         What level of technology exists for weaponry? Does it vary in different parts of
the world? Are there restrictions?
         What level of medicine exists? Who does the healing? What technology is
involved? If magic exists, is there magical healing?
         What level of law enforcement exists? Is there a structured legal system?
         How is local trade carried out (money or barter)? What about trade between
countries? What monetary systems exist?
         What range of education is available? What is the average level? What specialized
education?
         What, if any, is the cultural significance of:
Arts
Entertainment
Leisure activity/Architecture
Fashion/Dress
          What forms do they take?

Religion
         How does religion exist in this world, if at all? Does it impact the story?
         Do different races have their own gods? What are they?
         Do technology/magic and religion co-exist peacefully, or are they in conflict?

Time
         What calendar or other methods of measuring time are used?
         What are the major festivals or holidays?