A defined benefit pension plan generally cannot begin distributions until the participant has terminated employment. However, plans can (and many do) allow a participant who has reached normal retirement age to commence receiving benefits, even if the participant is still employed. Similarly, many plans offer an early retirement feature. Could a participant who qualifies for early retirement, but is still employed, elect to begin early retirement benefits? It strikes me as a real administrative pain for the plan, but it seems a plan could offer it if it wanted to. Any thoughts appreciated.

I don't think so.

I think your first two sentences are an answer to your question. In general, a qualified plan pays benefits upon the occurence of an event: death, disability, retirement, severance of employment. The exception is, as stated, attainment of NRA.