Attendance Policies

I'm running into attendance issues with my frosh-level classes this semester. As a graduate instructor, I had a relatively strict attendance policy. Students got a small number of freebie absences (regardless of reason and not requiring documentation). If they exceeded these, their grade was affected. As faculty, I abandoned this policy. My thinking was that college students should be expected to do their own time management and prioritization. There is a lot of evidence that individual attendance is highly correlated to course mastery measured in a number of ways so I trusted that those who chose not to attend regularly would likely get their just deserts. If they did well anyway, more power to them. Over my first five semesters as faculty, this revised policy has worked well enough. This semester, however, as I teach a course that is made up solely of frosh for the first time, I'm finding that the group interaction is suffering because significant numbers of students are chronically absent. Sadly, I think this means that frosh are simply too immature to police themselves. In other lower level courses, like my introductory class, which is comprised of a mix of frosh and sophomores with occasional juniors and even seniors, a course norm has tended to emerge organically. Students generate a sense of shared experience and cost that, even if weak, encourages regular attendance. Frosh, who are still all too accustomed to the strict constraints of high school, are unable to foster or recognize such solidarity. Compounding this for my frosh-level course this semester is my method of assessment. All of the coursework is done in groups, which means that the close relationship between attendance and success seems to be going out the window. Grudgingly, I've feigned heavy-handedness which seems to have scared some of the students back into compliance, but the most chronic of the chronic remain absent. Have others of you had luck with different strategies? I'd hate to revert back to my old policy.