Should your wah pedal go before your Distortion Pedal?
Yes, in most cases.
In most typical electric guitar setups, a wah pedal should go before a distortion pedal in what's called your "signal chain." This means that the signal starts at your guitar first, then goes into your wah pedal, and from there, your distortion pedal.

Ordering your guitar pedals is a big topic, with a lot of gray areas that can be difficult to pin down. The way I usually like to think of it is in terms of effect categories instead of individual pedals.
I go into that in a ton of detail in my guitar pedal setup post.
My article on how to start a guitar rig touches on this as well.
They might be helpful to you if you want to get more into the weeds on this topic and setup more than just wah and distortion pedals.
Though both those articles go into a lot of detail, so in addition to the short answer above, we'll go into a small amount of detail here on why your wah pedal should go before your distortion pedal in most cases.

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Wah and Distortion Effects Categories
Wah and distortion pedals are more properly understood in the following effects categories:
- Distortion pedals: Gain
- Wah pedals: Filter
There can be other gain and filter effects (boosts, EQ pedals, envelope filters, etc.), but we figure out our ordering based on those parent categories.
Conventional wisdom is that filter effects always go before gain manipulating effects, like a distortion pedal. This is because filter effects make changes to the frequency of your signal, like a high or low-pass filter.
Thus, these changes should come before you make changes to the gain, which basically means running up volume and then capping it off, creating the distortion and saturated sound.
Here's a graphic showing this order based on categories:

In an electric guitar signal chain, filter effects should always be placed before gain effects. Thus, wah pedals (a filter effect) should go before distortion pedals (a gain effect). Image is free to use but please credit with a link to our home page.
Same with overdrive and boost pedals?
Some might make a case for a signal booster to go before a wah pedal, but I would probably advise experimenting with that, based on the particular booster pedal you're using.
An overdrive pedal is simply a different style of gain effect, so it should go behind a wah pedal, just like distortion.
The same would go for fuzz pedals.
What about a compressor?
Compressors are a bit tricky in the pedal context. If at all possible, we'd recommend using a rack-based compressor instead of a pedal. However, if you do run a pedal, you'd probably be better off putting it first in your signal chain, in front of your wah pedal and filter effects in general.
That way your wah pedal is manipulating an already compressed signal, instead of compressing your wah effect.
Though take this one with a serious grain of salt.
Pedal compressors are weird.
Does putting a wah pedal behind distortion change the sound?
In my experience, yes.
While this of course depends on a lot of variables, I've tested this and found the distortion-before-wah arrangement to sound more like a fuzz pedal. It even seems to "hollow out" the tone and make it more raspy.
In some cases you might want that sound, but it's certainly not broadly usable.
Conclusion
To wrap this up, putting your wah pedal before your distortion pedal is always going to be considered a best practice in the world of guitar effects. Pay attention to categories and order pedals accordingly.
Unless of course, you have a specific reason to break with convention.
If you have questions about wah, distortion, or ordering your effects in general, feel free to jump in via the comments section below.
We also have a forum now that can be used for questions.
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Written by Bobby on Pedals and Roundups
Written by Bobby on Pedals and Roundups
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