Halloween has always been a time for people to choose a costume and become someone, or something else for the evening. However, many people don't want to stop at designing a single costume concept for All Hallow's Eve, and instead they get their friends in on it. This is usually referred to as a group costume because while each individual might be impressive, it's when the group is put together that the time, effort, and fun is magnified by the theme of the group costume. However, coming up with a group costume does have a few barriers that everyone interested in the idea should discuss. If your costume concept is going to involve some basic sewing and you've never held a needle before, don't panic! You can learn everything you need to know in just a few hours with Sewing 101.
The first difficulty is finding a group of people willing to do a group costume. 3-4 people is the average size of a group costume, since 2 people is considered a couple's costume, and with 5 or more people it becomes difficult to find a theme, though there are some that are made for larger groups.
The next step in the process is for everyone in the group to decide on a theme appropriate for the tastes of the participants, and for the event they'll be going to. Children may be more limited in their decisions than adults, for instance, both because of funds and because of what is considered "proper" costuming etiquette. Some examples of themes could be; The Fantastic Four, The Three Stooges, The Four Horsemen of the Apocalypse, The Seven Deadly Sins, etc.
Once the group has chosen a concept, or at least a theme (such as "all of us will go as old Norse gods", or "each of us should pick a villain from Batman's rogues gallery"), it's time to decide which member of the group will costume each particular character. This is where a lot of creativity needs to comes in, because group costumes can be expensive. As a result, tweaking and re-design can often become an interesting and integral part of the process of coming up with a group costume. Say a group wanted to do the Four Horsemen, but they didn't want to make entirely new costumes, so they modernize the theme. Pestilence is wearing a hospital Johnny, Death is a stockbroker in a black suit, War is dressed in modern fatigues, and Famine is wearing an all you can eat bib and vastly oversized clothes.
After the theory and design's finished, it's time to enjoy Halloween, and really show off all the work put into a group costume.