We present a structural dynamic non-linear model for an efficient cont
racting between a firm facing adjustment costs on labour and a union h
aving preferences which are subject to habit formation. The model's fi
rst-order necessary conditions are estimated for the French, the Dutch
and the Belgian labour market. The estimation results turned out to b
e remarkably similar for the three countries. Two alternative hypothes
es are also investigated: (i) a myopic behaviour of the union and (ii)
a competitive labour market. The performance of the efficient contrac
t model with a forward-looking union is found to be superior to that o
f the neo-classical model in explaining the dynamics of employment and
wages in the three countries.