Stanford's preservice Secondary Teacher Education Program (STEP) undertook a self-study to investigate how its credential candidates who had previous teaching experience perceived the value of returning for formal preparation. Using a semi-structured protocol, 23 STEP graduates were interviewed from 1999 and 2000, asking them about their teaching experience prior to STEP and any training they might have had; their year of STEP study; and for 1999 graduates, their first year back in their own classroom since graduation. A significant percentage of STEP candidates are already experienced teachers: 21% from the graduating classes of 1999 and 2000. Five themes emerged from interviews as vital areas of learning for these experienced teachers: (1) increased effectiveness working with struggling students; (2) greater sophistication in curriculum planning, particularly in identifying and matching long-term objectives and assessment; (3) greater appreciation for collaborative teaching and ability to nurture collegial support; (4) structured opportunities for feedback and reflection on teaching practice; and (5) development of theoretical frameworks to support teaching skills and learning. This article focuses more pointedly on what the study results suggest about STEP itself. How did the specific elements of STEP--coursework, field placements, major assignments, program structure--contribute to the five vital learning experiences described by this important subset of STEP candidates? (Contains 2 notes.)