Her Majesty looked smart and stylish in a light blue coat and matching had for the ceremony at St George's Chapel.
The service was obviously missing the the Duke and Duchess of Cambridge, who are currently enjoying their Royal Tour of New Zealand and Austtralia, and attended their own service in Sydney.
But other royals attended the Berkshire service, including the Duke of Edinburgh, Sophie, Countess of Wessex, Princess Anne and Princess Eugenie.
Princess Eugenie is back on British soil for Easter, after spending the last few months in New York, where she is working at the online auction house Paddle8.
While Stateside, Princess E has been showing off an array of cool looks, recently proving she has winter NY street style down in a cool leather skirt and fur scarf.
And she's also been making the most of the buzzing social scene. Back in February, she hit New York Fashion Week and sat F-ROW at Nonoo's Fall 2014 show donning a navy dress and popping pink lips.
And, that same week, she was spotted getting ultra-glam and was a dream in green at the 2014 New York amfAR gala at Cipriani Wall Street.
More recently,she donned a chic monochrome number for the Laduree Luncheon with Faberge at the newly opened SoHo tea salon in New York.
And there was also some quality time with Fergie, the Duchess of York, at the Gavel & Grand charity benefit auction at New York's Bowery Hotel in the run-up to Mother's Day.
LOVE PRINCESS E? Discover more of her style pics in our gallery below:
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