Synagogues, including Temple Kol Tikvah in Woodland Hills, held services marking the arrival of the year 5780 on the Hebrew calendar.
The holiday begins a 10-day period of repentance and reflection, ending with Yom Kippur, a day of atonement.
Rosh Hashana is also a time to gather with family.
Celebrations for the holiday include festive meals featuring apples dipped in honey, symbolizing wishes for a sweet year.