The term reconstructionism (or simply recon) can be applied to several different Pagan religions, though it is most often seen with Celtic, Norse or Greek paths.
Wicca is not a recon religion, because of it’s relatively modern origins and the fact that it was created from a combination of other practices. As I just mentioned, the most common recon paths are Celtic Reconstructionism, Hellenismos (Greek), Asatru (Nordic) and Kemetic Faith (Egyptian). Now, keep in mind that just because you worship Norse or Egyptian Gods doesn’t mean you can say you are following their faith. A reconstructionist approach involves much more about the original culture, not just the Deities.
Unlike many Wiccan or Wiccan-like paths today, reconstructionism isn’t about doing ‘what feels right’ or about finding a unique path that suits you personally. It’s not about eclecticism, or mixing and matching spiritual practices. Just at the term says, it’s about reconstructing the Pagan religions of ancient times with as much historic accuracy as possible.
Those who desire a recon path spend a lot of time doing research into the practices, culture, beliefs, attitudes, and values of the people who actively lived and worshipped in the past. This can require quite a bit of heavy academic study, rather than just picking up the latest paperback at the New Age store.
Rituals and ceremonies are based on those performed in the past, rather than created at the whim of the practitioner. Unfortunately, not all cultures have left behind enough written documentation to allow for complete accuracy, so some license must be taken to fill in the holes.
It may seem like this is more of a history research project than a religious following, and I suppose if you feel the academic side is too rigid for you, then you are just not suited to be a recon.
So, does the added level of historical accuracy make reconstructed religions more valid than those not steeped in age-old documentation? I don’t think so. There are infinite ways to approach Deity in one’s life and I prefer not to rank one path over another.