After decades of dramatic growth worldwide, international missionary shortwave radio is facing the prospect of downsizing due to rising costs and shifting mission priorities.

In 1931, Clarence Jones and Reuben Larsen, founders of pioneer station HCJB, launched modern-day missionary radio in Ecuador using a tiny 250-watt transmitter. Today, missionary radio is broadcast around the clock on stations worldwide, using state-of-the-art technology. Ranging from powerful international shortwave transmitters used by HCJB, the Far East Broadcasting Company (FEBC), and Trans World Radio (TWR) to local am and fm facilities, Christian radio now covers much of the world with music, church programs, preaching, and news.

Yet the success of missionary radio has not protected it from hard times. And experts are asking whether it will continue in its present form or radically remake itself. After years of expansion with new shortwave transmitters and the construction of powerful relay stations, some Christian broadcasters are scaling back, shutting down certain operations, and branching out into new areas.

Four months ago, San Francisco's shortwave station KGEI, a ministry of FEBC, shut down, ending nearly 40 years of transmitting to South America. Earlier, KGEI had stopped transmissions from California to the former Soviet Union as broadcasters who helped pay the bills turned their focus to placing missionaries in Russia rather than beaming broadcasts there from outside its borders. A year earlier, TWR terminated its shortwave broadcasts from the Caribbean island of Bonaire, citing high power costs and refocused priorities.

The move away from what Southern Baptist Theological Seminary professor Robert Don Hughes calls "the big drum approach," ...