A study of the Galactic distribution of IRAS Compact Molecular Clouds
suggests that the lifetimes of molecular cloud cores are commensurate
with the observed lifetimes of molecular outflow sources and the ages
of the youngest star clusters. Also the rate at which the gas and dust
is removed from the molecular cloud core by the formation of stars and
the dynamical processes observed to be associated with star formation
is an important factor in determining the star formation efficiency.
Rapid removal of gas and dust and the formation of bound clusters
suggest high star formation efficiencies, whereas lower star formation
efficiencies are indicated by slower removal of molecular gas and dust
and the formation of unbound clusters. It is proposed to use ISOPHOT
to observe open star clusters within the Galaxy to detect the remnant
dust from the parent molecular clouds. The purpose of these
observations is to investigate the mass ratio of remnant gas and dust
to stars in young open clusters with ages in the range 10^6 to 10^8
years) to:

1) determine how long the star formation process continues after the
   cluster emerges from the molecular cloud core and,

2) determine the relationship between star formation efficiency and
   cluster richness.

Since most of the emission from dust associated with star formation
is in the FIR, the proposed observations with ISOPHOT present a unique
opportunity to perform this investigation.