Nowadays, a considerable amount of time, money, and energy is invested
in inservice education or training (INSET). Yet, our knowledge of des
ign features and implementation conditions in schools that make INSET
effective, is still limited. To examine the outcomes of inservice acti
vities the impact ratings of a sample of teachers and principals who p
articipated in individual-based and school-focused INSET were regresse
d on school characteristics, features of inservice programs, implement
ation characteristics, and types of inservice activity. Findings from
this study suggest that some school characteristics, features of inser
vice programs, and implementation characteristics contribute to the im
pact of inservice training. Variables like external support, hours spe
nt on INSET activities, degree of participation, teacher educators' co
mpetence, implementation conditions, and the use of principal's steeri
ng functions are subject to alteration to increase inservice training
effectiveness.