Wonder Valley is a sparsely populated unincorporated community in the Morongo Basin of Southern California's High Desert region, straddling Amboy Road and State Route 62 in San Bernardino County, California, United States, approximately 10 miles (16 km) east of the city of Twentynine Palms.

Wonder Valley's subtropical desert climate is characterized by very hot summers and cool winters with considerable diurnal temperature variation throughout the year.

Wonder Valley is approximately 15 miles (24 km) northeast of the east entrance to Joshua Tree National Park.

[1] Many residents of Wonder Valley live on large parcels of land consisting of 5 acres (2 ha), a result of the community's growth after the enactment of the Small Tract Act of 1938.

[3] Wonder Valley was not substantively populated until the United States Congress approved the Small Tract Act (STA) of 1938, a homesteading law that facilitated the leasing and public-to-private transfer of ownership of parcels of up to five acres to United States citizens willing to improve the land by developing a residence, business, or recreational structure.