This is a GradHacker post by Terry Brock, PhD candidate in Anthropology at Michigan State University, @brockter
Professional service is one of the many elements of becoming a professional that many graduate students don't consider to be an important component of graduate school. It often slides under the radar, somewhere well below writing, research, and teaching. While almost all students understand the importance of joining professional organizations, attending conferences, and presenting at those conferences, few take their involvement beyond that step. However, there are many different ways to be involved in your professional organization, and a number of important reasons to do so. Many graduate students don't know how to become involved, or what options for student involvement exist. And, like anything else, taking on service responsibilities has its drawbacks.
Professional service can take a variety of forms. First, there is the size of the organization. For example, my first taste of professional service was a president of a local chapter of a public society. Our chapter almost entirely consisted of graduate students, and therefore run by them. While there were limited responsibilities, I was able to network with other archaeologists throughout the state, and our chapter served as host of the annual conference.
The larger the organization, however, the less likely graduate students will be able to hold "important" positions. However, this doesn't mean you can't make an impact on your discipline, or set yourself on a trajectory to make some waves in the future. My professional organization  has multiple subcommittees that are for and led by students, and offer wonderful opportunities for graduate students to influence the opportunities provided by the organization for students. Similarly, graduate students can be members of regular committees, participate in workshops, host round tables at conferences, or volunteer as part of the conference organizing committee.
The process of getting involved requires some research, and networking. Visit your organization's website and look at how it is structured, and what types of opportunities exist for members to be involved. Talk with your faculty members about how they are involved in their organizations, and discuss ways you may be able to be involved in ways that highlight your skills. My initial involvement (and current involvement) has little to do with my experience in my discipline, but everything to do with my skill set as a user of social media. I was able to identify a skill set of my own that has been useful to my organization, beginning with building a social media program for conferences, and now for the entire organization . Similarly, you may have interests in various elements of your discipline that are represented, or not represented, in your organization: discussing with your faculty members and peers about these areas, and how to be involved may reveal an opportunity for you to become involved in either a supporting or leadership position.
Of course, being involved is going to take time, and that time is something that you need to take into consideration. Rarely is involvement compensated, so you have to weigh the value of your involvement against the time your not spending on other things. I consider a number of elements when I weigh the time I dedicate to my society against my graduate work: Am I making a difference in my field and organization? Is my work being valued by my peers? Is my service resulting in building a sizable and valuable network within my profession? Is it resulting in new opportunities to expand my interests? Is it having a noticeable effect on my production as a grad student? If I don't feel as if my involvement is helping both my career and my organization in the amount of time I've allotted for it, then I need to reevaluate my involvement.
A final tip is to ensure that you have built a support network within and outside the organization. This is important for a number of reasons. First, as grad students many of us have not been part of the organization long: there is a culture to learn, politics to navigate, and the "right" and "wrong" people to discuss your ideas with. Finding allies within the organization will help you navigate these difficult and sensitive areas. Second, you need supporters to vouch for the importance and quality of your work: if you are working on a project, it is important to have supporters who are well connected to talk about and encourage what you are doing and why it is important. Lastly, it's important to have professionals who are removed from the organization so they can provide a third-party perspective. Self evaluation isn't always effective. There have been instances where all three of these elements have been critical to ensuring that my work is valued and that it is being done effectively.
In all, professional service is a critical part of building a professional network, establishing your position within your field, and providing an avenue for you to contribute to the advancement of your discipline. Even if this comes in the form of volunteering at a conference, or if you are serving on a committee, each moment involved in service will ensure that you are working with other professionals in your discipline, helping your organization achieve its goals, and will teach you about how these organizations work. When you finish your graduate program, having a solid footing within your discipline will allow you to hit the ground running.