THE inquiry into clutch and brood-size in the robin (Erithacus rubecula), which was first reported by David Lack in 1946, has now been closed. Later observations show that the breeding season in Holland is later than in Britain but is earlier in North France, Germany and Switzerland than inland in Europe at a similar latitude (British Birds, 41, No. 4 ; April, 1948). The tendency for the average clutch-size of the robin in England and Wales to be highest in May, lower in April, and lower still in March, June and July has been confirmed It has also been shown that the average clutch-size is different in different years and there may be a correlation between fine weather and higher clutch-size. The average clutch-size in Ireland is approximately the same as in England and Wales, but in Scotland the average clutch-size is higher than in England and Wales. Nesting is more successful in May than in April, possibly because in April the ground vegetation is not so well grown as in May, leaving the nests less exposed to predators.