"Should we do one long form or multiple shorter forms?"

"Lowering the barrier of entry" should not be equated with "one form or many"

When considering registration/sign-up with clients, there is a spectre floating about the room, the "Lower the barrier of entry in order to prevent drop-offs" spectre. This is a very good thing. Just ten years ago, I remember being told in no uncertain terms that we had to "force" users to give us as much information as possible. What is interesting to me now though, is that this "how to lower the barrier of entry" question has started to become synonymous with "should we do one long form or multiple short forms".

Don't Lose Sight of the Single Most Important Principle

Before I give my answer to that question, I would like to take a moment to remind folks that the single best way to lower the barrier of entry is to -- ask only for the absolute minimum amount of information you need. Honestly, every other form consideration is secondary to that single guiding principle.

Think you already are? Try looking again. Or have a relative or neighbor look with you. None of my relatives create websites. They are very helpful for seeing sites with fresh eyes..

Common Reasons Folks Use Form Processes

Now, back to one form versus multiple.... Let's start by looking at the thinking behind using multiple short forms rather than one longer form.

I believe the thinking is as follows:

A process can better 'draw users in' by showing them a quick and easy first step, rather than overwhelm them with a whole form.
Better grouping of questions
Give users an understanding of the process and their location within that process

Drawing users in...

This is an interesting one... Yes, you can draw people in by giving them a tantalizing short form that only asks for email and password. That's a pretty low barrier to entry and very appealing to users. I have often been drawn in, myself. But what happens next can be not so appealing. The user clicks submit on that first tiny form or a form widget and is now taken to a much longer form or finds themselves suddenly in a form process. Often, those minimalist group of questions are repeated on the longer form, pre-filled of course, but the user feels tricked! Email and password were NOT the only things you were going to require of them. They have already started, but do they really want to continue?

OK, so you don't do that, maybe you give them process indication from the start and you know that each step in the form is only 3-7 fields of information. Chances are pretty good that there is at least one question on each step that you have to "require". So, although you know your process is very reasonable, your user doesn't know that. It is locked behind the required fields from step one. Unfortunately, you may suffer from your users having been "burned" by other, less forthright, sites in the past.

Better Grouping of Questions

This to me is the most compelling reason to separate form elements into multiple steps. Especially in a situation where the path might fork or cycle based on user responses. For example, if you have a shopping cart and a user has added 2 or more items to their cart, during check out, it might make sense to ask if there will be multiple shipping addresses and if so, go to an address form as often as needed to accommodate your user's shipping needs. This allows for better grouping of related information and keeps things easy for the majority -- those who ship to just one address.

Give users a better understanding of the process

Again, I will risk stating the obvious -- if you have a one page form, then the process is immediately obvious. To me, this isn't really a reason, it is a necessary "by product". Don't create a process in order to illustrate the process. If you need a process (to group or isolate questions in the best possible way) then it is important to make that process clear to your users.

My answer...

So, my answer to this question... If there isn't a compelling reason to use multiple forms in a process -- use one long form. Possible compelling reasons for using multiple forms include:

Better grouping of questions
Isolate questions that only some of your users will have to answer (multiple shipping addresses)
Form gets too ungainly (more than one page below the fold might really be too much). But again, look at what you are asking. Do you really need to ask everything on that page?