Neff was a student of architect Ralph Adams Cram and drew heavily from the architectural styles of both Spain and the Mediterranean as a whole, gaining extensive recognition from the number of celebrity commissions, notably Pickfair, the mansion belonging originally to Mary Pickford and Douglas Fairbanks.
However, he spent a great deal of time at the Altadena residence, a grand Queen Anne Victorian mansion that looked from the hillside community down to the Pacific Ocean.
Eventually he found himself ready for the architectural realm creating designs of the Spanish Medieval period including his own home parish of St. Elizabeth of Hungary Roman Catholic Church, established 1918 in Altadena.
The view from its broad portals at 100 feet gave an enormous panorama not only of the Southern California countryside, now blocked by the since-built steeple of Westminster Presbyterian Church to its south, but an expansive view of the San Gabriel Mountains to its north, which boast peaks as high as 10,000 feet in altitude.
To the parish plant Neff added the priests' rectory, the convent for the Holy Name Sisters who taught at the school, and a pet project, a shrine to Saint Theresa of Avila (1929) which features the true style of his architecture.
[3] As Neff's style became more popular and demanded by the elite, the rich, and the famous, he moved to the exclusive Pasadena suburb of San Marino.
Neff's Angelo Drive house for the film director Fred Niblo, Misty Mountain, features a distinctive circular driveway and has been virtually unchanged since its construction.
Though the design did not gain support in the United States, it was used for large housing projects in Egypt, Brazil, and West Africa during the 1940s and 1950s.