ORIGINALLY COMPRISING ALL OF NSW WEST OF THE BLUE MOUNTAINS AND LATER REDUCED BY DETACHMENT TO THE CENTRAL-WESTERN SLOPES AND PLAINS. ENLARGED BY THE ADDITION OF LITHGOW IN THE LATE 1900's. AS NOW CONSTITUTED THE DIOCESE RUNS FROM LITHGOW TO COWRA, NORTH VIA EUGOWRA TO COONAMBLE THEN SOUTH-EAST TO DUNEDOO AND SOUTH TO LITHGOW.

THE DIOCESE COMPRISES THE NORTHERN SUBURBS OF SYDNEY FROM THE PACIFIC OCEAN AT MANLY VIA NAREMBURN, EPPING AND CARLINGFORD TO THE HAWKESBURY RIVER AT WISEMAN'S FERRY AND THE CENTRAL COAST FROM WISEMAN'S FERRY TO THE SOUTH SHORE OF LAKE MACQUARIE AND BACK TO THE PACIFIC OCEAN.

IN 1847 THE DIOCESE CONSISTED OF MAITLAND ONLY. IN 1866 IT WAS EXTENDED TO COVER THE HUNTER VALLEY AS FAR AS TAMWORTH. COONAMBLE WAS ADDED IN 1876. IN 1887 IT WAS REDUCED TO THE HUNTER VALLEY. IN 1965 IT WAS EXTENDED TO CATHERINE HILL BAY. IN 1976 KENDALL WAS TRANSFERRED TO LISMORE. AS NOW CONSTITUTED IT RUNS FROM SWANSEA TO CASSILIS, THEN TO MURRURUNDI AND EAST TO HARRINGTON.