Paper describes chlorophyll a fluorescence measurements in algal cells, and intact plant leaves and isolated chloroplasts. It focuses on amplitude and 10μs-resolved kinetics of variable fluorescence responses upon excitation with fluorescence-saturating pulses (SP) and with 25μs saturating single turnover flashes (STF) which are exposed before, during and after a 100s actinic illumination (AL) of low and high intensity. In addition to the amply documented suppression of the maximal variable fluorescence from F m to Fm′, the relative proportion of the distinguished O–J-, J–I- and I–P-phases of an SP-induced response is shown to be distinctly different in dark- and light-adapted leaves. The O–J-phase in the 0.01–1ms time range is much less sensitive to light adaptation than the other phases in the 1–200ms range. In algae and chloroplasts, the amplitude FmSTF of the STF-induced response is hardly affected by a shift from the dark- to the light-activated steady state. The results support the hypothesis that the maximal variable fluorescence F m induced by a multiple-turnover, fluorescence-saturating pulse (SP), is associated with the release of photochemical and photoelectrochemical quenching. It is argued that the OJIPMT- or Kautsky induction curve of variable chlorophyll fluorescence in the 0–100s time range is the reflection of the release of photochemical quenching supplemented with a temporary Photosystem I (PSI)-dependent photoelectric stimulation and transient release of photoelectrochemical quenching of radiative energy loss in the Photosystem II (PSII) antennas, rather than solely of a decrease in PSII photochemical activity as is usually concluded.