Evaluation is the process of analyzing whether or not your initiative has achieved the desired outcomes, and why. It is crucial to the field of prevention that we are able to demonstrate, unequivocally, that our strategies can be successful and produce desired outcomes. If we don't measure what we do, we'll never have the evidence we need to show that prevention works. Therefore, prevention, as a field, has been embracing evaluation so that we will have the scientific evidence to back up our convictions.

It is important to plan for evaluation before you start implementing your initiative. Furthermore, evaluation should be a process that continues on a regular basis throughout the life of your project - that way you will always be informed about whether or not your initiative is on the road to achieving its goals. Evaluation is crucial to prevention because it tells us what works, what doesn't work, what to improve, and how to improve it.

In evaluating your work, you need to be just as diligent about developing a solid evaluation plan as you were at planning your prevention initiative. And, a solid evaluation plan will help you to monitor the progress of your initiative as you go, so that you can make improvements along the way, if necessary. An evaluation plan also helps you to (1) identify the data that needs to be collected as your initiative moves forward, (2) how frequently you should be collecting that data, (3) what instruments you should be using to collect the data, and (4) who should be responsible for data collection. A good evaluation plan also helps promote good communication between those responsible for carrying out the evaluation plan, and those implementing the project, as well as other stakeholders interested in knowing how things are going.

There are two types of evaluation, process and outcome. If you are analyzing issues around the implementation of your initiative, you are doing a process evaluation. If you are analyzing issues related to the outcomes of your project, you are doing outcome evaluation. It is best to do both a process and an outcome evaluation. If you only do a process evaluation, you won't find out how the initiative is affecting the problem you set out to solve; if you just do an outcome evaluation, you won't find out what areas in the project design are working better than others.