Since Nika has done a good job of summarizing the chapter, I will explain the modes of belongining in the Fighting 44s.  In engagement, the Fighting 44s participate in discussion of various topics.  In fact, one of the discussion threads in the Introduction section is entitled "What made you a Fighting 44?"  This thread is devoted to people sharing their experiences and why they decided to participate in the F44 community.  For imagination, the Fighting 44s do several things.  The first is they have galleries for photos and art that members can rate and provide feedback on (as Wenger would put it, "assuming the meaningfulness of foreign artifacts."  Also in the discussion area, there are specific areas to share stories and experiences.  There are specific areas to discuss the Fighting 44 community, content, and other areas in the feedback to articles threads and in the Wetwork section.  As for alignment, this actually affects both the Fighting 44s and the greater North Asian American community identity that is part of the joint enterprise.  

Summary

This chapter is about how people form identities in communities through participation and non-participation.  As I understand it, non-participation does not mean not allowed or not accessible to the community.  Non-participation means some sort of interaction, just not in a full or complete way.  If I read Wenger correclty, non-participation provides a source of information about what we are not.  I guess what we are missing out on for various reasons (no desire, no capability, etc). Non-participation is inevitable since we live in and encounter many communities of practices so it is not possible to fully participate in all of them.  There are two types of case of interaction of participation and non-participation.  One is peripherality where some level of non-participation is required to order to enable full participation.  I suppose a good example is job shadowing when you first start a job.  You shadow a more experienced co-worker (non-participation) in order to learn the job so you can eventually do it and contribute (full participation).  The other interaction is marginality, where forms of non-participation prevent full participation.  Wenger then describes that participation and non-participation help define our identities and our relationship to the rest of the world such as what we hold as priorities, what we care about, who we associate with, and what we spend out time on.

Chapter 6 presents an introduction of identity as how we see the world in ways that are shaped by our involvement in a community of practice. We interweave various aspects of the community of practice to form our identity:

• Negotiated experience
• Community membership
• Learning trajectory
• Nexus of multimembership
• A relationship between the global and local

Others have already blogged about (or drawn!) what these mean in the author's view, so I am going to apply them to one of the communities I have been studying, Geocaching.com.

Negotiated experience
Geocachers indicate their identity with the geocaching movement by participating in the practice of geocaching. They identify with a particular way of treasure hunting using specific artifacts and sense of adventure. This differs from those who wander aimlessly through the woods and happen to find a treasure or interesting place they haven't seen before. By being a geocacher, one identifies as someone who is on a hunt for interesting locations, for history, for nature using artifacts such as GPS data and written hints. These artifacts reify what it means to geocache, and represent the contributions that members have made as they define their identity in the community.

In this chapter, Wenger focuses on identity in terms of three modes of belonging that do not directly involve engagement in practice: engagement, imagination, and alignment. Wenger's argument here is that our identity does not just exist within the confines of belonging to our community of practice ("I belong to the Alinsu claims processing group"), but that it extends to the broader social realm in which we exist ("I belong to the field of claims processing"). To feel belongingness at such a global level, members:

• are actively involved in a mutual process of negotiation of meaning
• extrapolate from their own experiences to imagine how their social world exists
• align their energy and activities to fit within this broader social world

More about each of these follows:

This chapter discusses what identity is over the concepts introduced in Part I of the book, drawing parallels between practice and identity. This analogy is refined in the following chapters of the book.     

Identity as negotiated experience

Identity shouldn’t be equated with reifications like social categories, or self-images. It is defined socially also because it is produced as a live experience of participation in specific communities. Our identity is a complex interweaving of participative experience and reificative projections (151). Our experience and its social interpretation inform each other in the process of negotiation of what it means to be a human and ourselves.

Identity as community membership

Our membership constitutes our identity through the forms of competence. Different levels of memberships imply different level of competence. Dimensions of practice introduced in Chapter 2 is used as dimensions of identity:
•    Mutuality of engagement – individuality is defined differently depending on how members interact in that community
•    Accountability to an enterprise – gained perspectives resulting from investment in the enterprise
•    Negotiability of a repertoire – our personal history of participation enable us to interpret and make use of the repertoire.
 
Identity as learning trajectory

Identity is not a stable object, but a constant becoming (154). Identity is temporal, ongoing, constructed in social contexts (hence its temporality is non-linear), and defined with respect to interacting trajectories. There can be various types of trajectories:

I want to think about cult groups, where their imaginations strengthen engagements, and engagements strengthen imaginations, and when the mode of belonging to such strengthened imaginations move its dominance to alignment mass suicide happens.

In the above case, it seems that the members' imaginations are so vulnerable to engagements. I wonder if the nexus of multimembership can help reduce excessive polarization of the imaginations formed in the community.

To me, what Wenger describes as "modes" of belonging seem to be more like "modes" of thought. 

Engagement represents the "now" mode where the member is fully engaged

Imagination represents the "future" mode where the member is free to think about which trajectory to take and what possible new trajectories he could form.

Alighnment represents the glue that bonds imagination with engagement to ensure that the community could work together towards a common enterprise.

The word "belonging" sounds funny.

Reading "some degree of non-participation is necessary to enable a kind of participation that is less than full" made me think of consulting companies who swoop in and try to solve a bounded problem for a company rather than getting fully involved in the work. 

It is that aspect of peripherality that allows them to gain a wide-spectrumn of knowledge (being able to free up resources to work on multiple projects as opposed to dwelling into one) and the ability to think "fresh."

I feel that a lot of
the concepts that Wenger bring up lack concrete examples (at least for me).

To help clarify the abstract
concept of trajectories, a concrete example can be formed around studying
through an academic major while at a university.

As we progress and take
more classes, we start to refine our identity (focus of concentration).
We also take peripheral trajectories (attending seminars) which we do
not fully participate in the area of study but our benefit of ignorance allows
us to give fresh views to the presenter's topic. People who take intro classes
to test the waters are on the inbound trajectories to becoming full
members. After becoming a full member, insider trajectories in the form
of specialized workshops / clubs become available. A student can also work on interdisciplinary
projects traveling down boundary trajectories. Students studying at the School of Information can is a great example of
following a boundary trajectory.

OK, although I'm the first one to write, I won't summarize since I have few questions to ask in order to understand what he is saying in this chapter.

1. Marginalization

Is marginalization a product of non-participation among old-timers? Or is non-participation a bad product of marginalized people (which in this case considered equal to old-timers)?

2. Non-participation

So, I see that non-participation can be understood in three different context:

1) one is within the same community where the participation of oneself is happening (e.g., new-comers vs old-timers: you don't have to do this yet since you are a newbie)