Being a school psychologist, I have the benefit of visiting a wide variety of schools in a given year. I have observed that campuses that have well developed parent and community volunteers often function at a higher level than those who don’t have the luxury of volunteers.
UCLA Looks at Parent Volunteers
Volunteers can have a very powerful impact on the students and schools. What follows briefly highlights some research on the benefits and ways to use volunteers and ways for schools to move forward in implementing volunteer programs.
What Research Says
Henderson and Mapp (2002) report evidence that volunteers can be significant resources in helping create a supportive and welcoming environment at schools and facilitating students’ behavior and performance. As positive role models and student motivators, volunteers are viewed as contributing to better school attendance, improved grades and test scores, matriculation, less misbehavior, better social skills, staying in school, graduating, and going on to college.
The Many Roles for Volunteers in the Classroom and Throughout the School I. Welcoming and Social Support
A. In the Front Office
1. Greeting and welcoming
2. Providing information to those who come to the front desk
3. Escorting guests, new students/families to destinations on the campus
4. Orienting newcomers
B. Staffing a Welcoming Club
1. Connecting newly arrived parents with peer buddies
2. Helping develop orientation and other information resources for newcomers
3. Helping establish newcomer support groups
II. Working with Designated Students in the Classroom
A. Helping to orient new students
B. Engaging disinterested, distracted, and distracting students
C. Providing personal guidance and support for specific students in class to help them stay focused and engaged
III. Providing Additional Opportunities and Support in Class and on the Campus as a Whole – including helping develop and staff additional
A. Recreational activity
B. Enrichment activity
C. Tutoring
D. Mentoring
IV. Helping Enhance the Positive Climate Throughout the School – including Assisting with “Chores”
A. Assisting with Supervision in Class and Throughout the Campus
B. Contributing to Campus “Beautification”
C. Helping to Get Materials Ready
Source: http://smhp.psych.ucla.edu/pdfdocs/vols.pdf
We recently piloted a behavior management system in one of our Special Education Classroom called 
Building Momentum in Schools 