A conceptual framework composed of eight categories of mentoring activities that address five domains of beginning teachers' concerns was developed based on the reported activities of 150 teachers who were lead mentors. The study suggests that experienced teachers possess an extensive repertoire of helping strategies and that, with opportunities for collaboration, teachers can develop and shape complex mentoring roles that meet beginning teachers' needs. Conditions that influence mentoring relationships include school context factors and mentor and beginning teacher characteristics. Mentoring programs thus should not attempt to rigidly specify mentoring roles. With support, experienced teachers can provide assistance tailored to the circumstances of beginning teachers in individual schools.