I can't seem to get my team members to complete their action items, let alone cooperate with the rest of the group. What can I do?
Though it's too late for this project, for future teams look for people who have an interest in the outcome of the project and the ability to contribute. If your team members don't care and don't have anything to contribute, get a new team.
Most well-managed projects have a few things in common. First, they have a predetermined schedule. If you know it's a 12-week project, determine the finish date and work back from there. Second, set up checkpoint meetings with team members in which you are very clear about project goals and individual responsibilities. Even if you do only these two things, you're increasing the chances of producing a better project. In addition, there are a number of good software packages on the market that can help you organize your project flow and set up checkpoints.
Take a hard look at your team and remove the bad apples. One troublesome person can derail an entire project. Worse, if it's a process that involves customers, it could hurt your customer relationships or your company's reputation.
There is almost always a root cause for this kind of behavior — this person may think they have a better idea, or they may consider themselves overqualified (or underqualified) for the team or project. Ask individual team members about their sense of how the project is going, and why problems have arisen. You should be able to piece together a good picture of what's happening. The important thing is to get to the root of the problem, and either fix it or move the person off your team.
Regardless of the reason for your team's ineffectiveness, don't let the bad situation continue. Address it as a team, or bring it to someone's attention before it hurts the business.