  We present theoretical results for the underscreened Kondo lattice model with
localized S=1 spins coupled to a conduction band through a Kondo coupling,
$J_K$, and interacting among them ferromagnetically. We use a fermionic
representation for the spin operators and expand the Hamiltonian in terms of
bosonic fields. For large values of $J_K$, we obtain a ferromagnetically
ordered solution and a Kondo regime with a Kondo temperature, $T_K$, larger
than the Curie temperature, $T_C$. This finding suggests a scenario for a
coexistence of Kondo effect and ferromagnetic order. In some uranium compounds,
like $UTe$ or $UCu_{0.9}Sb_{2}$, this kind of coexistence has been
experimentally observed: they order ferromagnetically with a Curie temperature
of order $T_C \sim 100K$ and exhibit a Kondo behavior for $T > T_C$. The
proposed underscreened Kondo lattice model accounts well for the coexistence
between magnetic order and Kondo behavior and yields to a new ``ferromagnetic
Doniach diagram''.
