- 1926: She graduates from university in Cardiff. Encouraged to go on to the Royal College of Music in London to study composition with Ralph Vaughan Williams and Gordon Jacob.
- 1930: She went to Vienna to study with Egon Wellesz.
- She taught at Camden Girls’ School in London and at Southlands College of Education and became close friends with Benjamin Britten.
- 1938: Publishes 'Fantasia on Welsh Nursery Tunes'.
- 1947: Returns to south Wales.
- 1949: She composed music for the film 'Blue Scar', which was directed by Jill Craigie.
- She composed incidental music for radio performances of plays by Saunders Lewis.
- Some of her works, such as the 'Trumpet Concerto' are considered to be some of the best of their time.
- 1966: Her one-act opera :The Parlour' is staged.
- Her manuscripts are preserved in the National Library of Wales, and the centenary of her birth in 2006 saw several performances of her works.
'Williams was born and died in Barry, and her current reputation as one of Wales’ leading composers was won largely
through vocal and orchestral music. She is credited by some for having composed the first Welsh symphony, and in 1949 was the first British woman to score a feature film, "Blue Scar".’ – Erica Jeal, 'Grace Williams: Chamber Works review – don't take this neglected Welsh composer at her word!', The Guardian, 7 March 2019 – https://amp.theguardian.com/music/2019/mar/07/grace-williams-chamber-works-review-neglected-welsh-composer-london-chamber-ensemble-mitchell-naxos