This overview from the American Evaluation Association's AEA 365 blog page, provides an overview of using waitlist control groups.
It includes a tip on how to use wait lists in a program that is going to use a pre and post-test.
"A design that may be a good compromise is the use of a wait list control group. With this design, all participants eventually receive the program or intervention, but the design still allows for the control of many variables (with the exception of the placebo effect). So, let’s say you are evaluating the effectiveness of a six-week program using a pre/post test. You would randomly assign your participants to either the experimental or wait list control group. Then, administer the pretest to all participants just prior to when the experimental group begins the program in week 1 (of course the wait list control group would not begin the program yet). Then, the experimental group would receive the program in weeks 1 thru 6 and you will administer the post test to both groups at the end of week 6. In weeks 7 thru 12, you will deliver the program to the wait list control group." (Jewell, 2011)
Jewell, J. (2011, January 30). [Web log message].Using wait list control groups in evaluation. Retrieved from http://aea365.org/blog/?p=2536
'Using wait list control groups in evaluation' is referenced in: