Why did my summer squash fall off the plant?

When young squashes fall off the plant it is likely a pollination issue. Squash are insect pollinated. The pollen has to be carried from a male flower to a female flower. If there were no insects to pollinate the plant, it will drop the unpollinated fruit. It is also possibly due to stress on the plant from heat or lack of water.

Related Videos:
Growing Summer Squash
Squash Pests

Related Resources:
Fruit Set Problems in Squash, Melons, and Cucumbers In Home Gardens
Yard and Garden: Solving Common Problems with Summer Squash
Hand Pollination of Squash and Pumpkins