  The first star formation in the universe is expected to take place within
small protogalaxies, in which the gas is cooled by molecular hydrogen. However,
if massive stars form within these protogalaxies, they may suppress further
star formation by photodissociating the H2. We examine the importance of this
effect by estimating the timescale on which significant H2 is destroyed. We
show that photodissociation is significant in the least massive protogalaxies,
but becomes less so as the protogalactic mass increases. We also examine the
effects of photodissociation on dense clumps of gas within the protogalaxy. We
find that while collapse will be inhibited in low density clumps, denser ones
may survive to form stars.
