I live in the tropics so I am not sure about your environmental conditions. However, when I get this problem it is usually related to using soil or fertilizer with too much nitrogen. I usually stop using any fertilizer with nitrogen and use blossom booster type fertilizer (high potassium). I also find using liquid calcium very helpful for preventing flower drop.
Sometimes too much shade could also be a problem.

So, could this still qualify as "blossom drop" even though pollination occured and fruits were set?

I use organic fertilizer, and not too much of it. Mostly using the higher-potassium kind.

Where do you find liquid calcium? I also read somewhere on the forum that magnesium can also help with this.

I do have shade issues, but I think the peppers are getting at least 7+ hours/day.

I wonder if wet soil could be an issue. I've amended a heavy clay soil bed with compost and lots of other 'good stuff,' but it is still very dense and has needed little (none, really) watering so far this year. Our temps have been lower than normal (70s-80s) and we've also had more rain than usual.

Thanks!
veg

Well it is not technically blossom drop but I think the fruits are not holding because of a possible lack of trace elements. Limestone can be used as a substitute for liquid calcium. Limestone also has traces of magnesium and will help.

Soil type may not be a problem as I normally plant in heavy clay here in the Caribbean and all is well. Actually I find peppers love this soil. I just loosen the soil around the plants every once in a while.

The temp seem to be in a good range but, I have found that excessive rain usually retards fruit production, especially Chinenses.

I think the calcium (limestone) will help strengthen the flower and fruit structures so try this first.

you can buy calcium and magnesium in liquid form at most hydroponic stores. However, you can also just put eggshells in the garden beds year round and use epsom salts for your magnesium if you need to.

I think it happens when the plants are too small and it may depend on what variety of plant it is. But there is certainly a chance it is due to nutrients and fromtobago seems to have more experience with that than I do.

Also seaweed extract is an excellent organic nutrient booster. Will not burn your plants but they look so much healther and happier when they are getting it. It contains all the trace elements that regular fertilizers don't give you

kendra

Kendra has a good idea with the seaweed extract. It is a wonderful organic nutrient source. It is a good general purpose booster and really contains a lot of trace elements.
Regarding plant size- in my experience once the plants start branching they are capable of holding fruit.