Every once in a while I see a reference to PLNs, PLCs and communities of practice that makes me wonder if I understand the similarities and differences between these three phrases.  While I admit that I do not have a full understanding of these ideas, I thought it might be helpful for my own thinking to flesh out a few ideas in writing.

Personal Learning Networks (PLN)
"A personal or professional learning network (PLN) involves an individual's topic-oriented goal, a set of practices & techniques aimed at attracting and organizing a variety of relevant content sources, selected for their value, to help the owner accomplish a professional goal or personal interest." -David Warlick, slide 4
"Personal learning networks (PLNs) are not new. We have long relied on our families, friends, colleagues, and acquaintances to supplement our knowledge about the world. Our professional learning also comes from reference books, the textbooks we carried home from college, the television and radio stations we tune in to, and the professional and personal-interest periodicals to which we subscribe. And we have been connecting with people and information through the digital realm for decades. But the times are still changing. Information and communication technologies (ICT), including an ever growing repertoire of open source applications, have freed content from the printed page, giving voice to the ideas of people we have never had access to before and enabling us to reshape our information experiences to suit our learning needs. Harnessing these new technologies to create and grow our own PLNs is imperative for educators who want to stay connected to the changing world we are charged with introducing to our students." -David Warlick (pdf)
Based on Mr. Warlick's definitions, a coin collector could have a personal learning network as might a doctor and elementary teacher.

While technology can play an important role in expanding and accessing additional resources in our personal learning network, I don't think today's digital tools define a personal learning network.  As an example, prior to joining Twitter several years ago, here's a snapshot of my PLN:

My goal was to improve as a high school math teacher.  I utilized professional journals, professional development (PD) opportunities, read publications and interacted with colleagues near and far.

Today, I am also able to learn through reading blogs, listening to podcasts, following conversations and links through Twitter, interacting with new and old friends face-to-face at conferences and video chat or talk on the phone with my siblings (and siblings-in-law) who are educators.  A PLN involves humans we interact with in person or virtually as well as the resources they create (i.e. blogs, journal articles, podcasts, conference presentations).

Professional Learning Communities (PLC)
"The idea of improving schools by developing professional learning communities is currently in vogue. People use the term to describe every imaginable combination of individuals with an interest in education - a grade-level teaching team, a school committee, a high school department, an entire school district, a state department of education, a national professional organization, and so on.  In fact, the term has been so ubiquitously used that it is in danger of losing all meaning."  - Richard DuFour 
So, what is a PLC?
"...an ongoing process in which educators work collaboratively in recurring cycles of collective inquiry and action research to achieve better results for the students they serve" - DuFour, DuFour, Eaker and Many, p. 11
From p. 14 of Learning by Doing, the essence of the PLC process is captured in three big ideas:

  1. The purpose of our school is to ensure all students learn at high levels.
  2. Helping all students learn requires a collaborative and collective effort
  3. To assess our effectiveness in helping all students learn we must focus on results -- evidence of student learning -- and use results to inform our professional practice and respond to students who need intervention or enrichment.
In other words, a professional learning community is a group of educators who are working together to improve student learning.  From my vantage point, PLC is an education-specific term.  The adults who form a collaborative team within a professional learning community would likely share one or more of the following in common: students and/or content.  For example, a team of third grade teachers or high school science teachers may form a collaborative team working towards the ideals set forth in the PLC process.  It would be less likely that a secondary P.E. teacher, a first grade teacher and a guidance counselor would form a collaborative team within the PLC framework.  In my experience reading about and leading a PLC process, these educators are often a part of the same building or school district, but may also cross building or district boundaries.  Three physics teachers from separate districts could form a virtual collaborative team that uses evidence of student learning to inform professional practice.  

Communities of Practice
"Communities of practice are groups of people who share a concern or a passion for something they do and learn how to do it better as they interact regularly." - Etienne Wenger
This group of people have an identified shared interest.  As Wenger suggests, "In pursuing their interest in their domain, members engage in joint activities and discussions, help each other, and share information." To use a phrase from the term itself, this group of practitioners share their resources and experiences with each other for the conscious or unconscious rationale of collective improvement.

Communities of practice appear to be present in education, government, professional membership associations, and in many other sectors.

Synthesizing PLC, PLN and Communities of Practice
First, I think it's important to note that at least two of these three terms are not specific to education. None of the three require digital communication tools, however these tools can surely enhance and expand opportunities for learners.

I think the definitions and examples above help me better understand the differences between these three terms, but how do they overlap and interact with each other?

Enter a fictitious middle school social studies teacher, Jane:

Jane is assigned to a collaborative team with other middle school social studies teachers.  This team regularly uses student assessment results to inform their professional practice (PLC).  Jane regularly lurks on Twitter and spends time consuming content through her RSS feed and several email lists (PLN).  On Saturday mornings, Jane meets for coffee with a friend from church.  They regularly discuss their shared hobby, quilting (Community of Practice).  Jane often shares the resources from her PLN with her PLC when brainstorming new instructional strategies to help students learn at higher levels.  Every once in a while, Jane shares her passion for quilting with her students and middle school social studies colleagues, because it's part of who she is as a person.

Wrapping up
The purpose of this commentary was to write down my thoughts surrounding three phrases that, in my opinion, are sometimes inadvertently used synonymously. It was also to suggest how they might often overlap and can supplement each other.   Last, I hope it served to deepen my own understanding of these three phrases so that I might become a better learner and help others do the same.