Not enuff water? Seed stock crossed? Variety?

Yeah variety name please. 50 different varieties at least. And define "relatively small". What is small size to you may be normal size to others or could be a pollination issue. Were these saved or traded seeds meaning they were probably cross-pollinated? Watering regimen?

Dave

These are yellow crookneck grown from seedlings. The adjacent plants are doing fine, producing normal, pale yellow fruit. Here's a photo of my orange, thin squash. Also, this particular plant was producing fine a week ago.

It isn't yellow crookneck, maybe yellow straight neck and yep, way past harvesting time and size and inconsistent soil moisture levels.

Dave

Actually, you're right... I remember now I planted two straight and two crookneck. I will blame this on the weather over the last few weeks... It was very hot and dry, but I was out of town so couldn't do much about it. But, it's rained quite a bit lately so things should get back to normal. I think I'll pick the orange ones and add them to the compost. I tried to cut into one yesterday and it's amazing how tough it was, compared to a squash that received adequate rainfall.