I need to find out about homesteading in Montana in the early part of
the 1900's, from about 1915 to 1930. What drove these people to move
to Montana? Why was it looked apon so positively initially and why did
become such a failer in the end?

Homesteasing in Montana took off for four big reasons.   First was an
expansion of the Homestead act that allowed filing on a full section
of land and then a shortening of the time to "prove up" claims.  
Second was the Great Northern Railroad of James Hill.  Hill's link
from the Twin Cities to Seattle across the nborthern tier of the
nation was accompanied by a great deal of promotion as Hill sought to
populate the land along his railroad.   His ads would depict Montana
as the proverbial horn of plenty.   This coincided with a great influx
of Northern European immigrants, who made up a majpor share of the
homesteaders.   Third was the advent of World War One which shot grain
prices to their highest level.    And fourth was an unusually wet
cylcle in the weather.    All of this combined to feed the drive of
homesteaders to Montana.

Two major things ended the boom.   In 1918 the World War ended.  At
that same time Montana cycled into a drought.   Farming practices,
taken from methods of wetter climates had destroyed the ground cover. 
There was nothing to prevent wind erosion of the soil.   Montana was
in a "dust bowl" well before the southern midwest.    Montana sank
into a depression a decade before the rest of the nation.  So many 
people flocked out of the  state between 1918 and the taking of the
1920 census that historians have estimated that as many as half of
those who flocked to Montana in the teens to homestead were gone
before they werre counted.   As it was, the teens still proved to be
Montana largest period of growth by percentage.   It changed the face
of the state.   Towns sprang up all over what had been mostly empty
rangeland and an orgy of county-splitting more than doubled the number
of Montana counties.  Some now have less than 1,000 population, with
very little business to sustain them.