| A Sanshey Electric INC | Anthony David Sanshey | — | (760) 743 6273 | Electricians | Escondido · San Diego County | — | — |
| A Satellite Source | A Satellite Source | — | (626) 780 9331 | Other | Rosemead · Los Angeles County | — | — |
| A Satin Touch | A Satin Touch | — | (818) 703 1266 | Windows, patio, painters | Canoga Park · Los Angeles County | — | — |
| A Scape Artist | A Scape Artist | — | (650) 759 2455 | Windows, patio, painters | Los Gatos · Santa Clara County | — | — |
| A Schaefer Construction | Andrew Alfons Schaefer | — | (650) 240 6448 | GC, remodel, ADU | San Mateo · San Mateo County | — | — |
| A Schuman Electric | Andrew Nathen Schuman | — | (760) 628 5249 | Electricians | Lucerne Valley · San Bernardino County | — | — |
| A Scott Birdsall Construction Co | Andrew Scott Birdsall | — | (805) 857 2746 | GC, remodel, ADU | Ventura · Ventura County | — | — |
| A Scott Building | A Scott Building | — | (707) 481 7088 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| A Second Opinion Garage Door Repair | Thomas Laurence Hesse | — | (760) 855 4670 | Other | San Marcos · San Diego County | — | — |
| A Second Opinion Plumbing | A Second Opinion Plumbing | — | (909) 437 7747 | Other | San Bernardino · San Bernardino County | — | — |
| A Sewer Guy Plumbing | A Sewer Guy Plumbing | asewerguy@gmail.com | (530) 313 7923 | Other | Bowman · Placer County | — | — |
| A Shade Above | A Shade Above | — | (951) 691 2018 | Windows, patio, painters | Temecula · Riverside County | — | — |
| A Sharp Builder | A Sharp Builder | — | (408) 259 7930 | GC, remodel, ADU | San Jose · Santa Clara County | — | — |
| A Shield Advanced Protection | A Shield Advanced Protection | — | (415) 238 7804 | Other | Novato · Marin County | — | — |
| A Siegfried Construction | Andrew Todd Siegfried | — | (925) 628 3282 | GC, remodel, ADU | Livermore · Alameda County | — | — |
| A Sign-scape | A Sign-scape | — | (714) 470 1136 | Other | Santa Ana · Orange County | — | — |
| A Skyline Communications | A Skyline Communications | — | (310) 413 0735 | Other | Culver City · Los Angeles County | — | — |
| A Smart Cleaning Services | Esteves Alicia | — | (916) 723 9511 | Other | Gridley · Butte County | — | — |
| A Smith Construction | Andrew James Smith | — | (720) 838-5307 | GC, remodel, ADU | Atascadero · San Luis Obispo County | — | — |
| A Soria Tile Company | Arturo Rangel Soria | — | (951) 283 1747 | Other | Riverside · Riverside County | — | — |
| A Sound Vision & Automation | A Sound Vision & Automation | — | (626) 242 6048 | Other | Upland · San Bernardino County | — | — |
| A Sousa Drywall Co INC | Albert Melo Sousa | — | (408) 438 7298 | Other | Los Gatos · Santa Clara County | — | — |
| A Specialist | A Specialist | — | (818) 355 0414 | Electricians | North Hollywood · Los Angeles County | — | — |
| A Specialty Construction Services | Richard Franklin Currie | — | (619) 829 6356 | GC, remodel, ADU | El Cajon · San Diego County | — | — |
| A Squared Construction INC | Joseph David Ballinger | — | (925) 826 5727 | GC, remodel, ADU | Benicia · Solano County | — | — |
| A Squared Painting | A Squared Painting | andy@asquaredpainting.com | (559) 288 1887 | Windows, patio, painters | Fresno · Fresno County | — | — |
| A Star Construction | Yaralyan Sarkis | — | (323) 497 1234 | GC, remodel, ADU | Los Angeles · Los Angeles County | — | — |
| A Star Plumbing | A Star Plumbing | andrey@a-star-plumbing.com | (916) 389 4022 | Other | Roseville · Placer County | — | — |
| A Step Above Flooring INC | Fred Allen Ruelas | — | (209) 571 8583 | Other | Modesto · Stanislaus County | — | — |
| A Step Above Painting Co | Gomez Jaime | — | (619) 463 9300 | Windows, patio, painters | Lemon Grove · San Diego County | — | — |
| A Step Above Painting INC | Todd Justin Knutson | — | (209) 526 1500 | Windows, patio, painters | Modesto · Stanislaus County | — | — |
| A Step Above Pest Control | A Step Above Pest Control | — | (323) 716-1725 | Pest, tile roofs | Los Angeles · Los Angeles County | — | — |
| A Step Beyond | A Step Beyond | — | (510) 228 8426 | GC, remodel, ADU | Modesto · Stanislaus County | — | — |
| A Step Up Enterprise INC | Michael Ray Dobbs | — | (916) 660 6241 | GC, remodel, ADU | Meadow Vista · Placer County | — | — |
| A Storseter Construction | Andrew Bernard Storseter | — | (650) 784 5964 | GC, remodel, ADU | Millbrae · San Mateo County | — | — |
| A Strouse & Son Glass INC | Russell Guy Strouse | — | (831) 394 2622 | Windows, patio, painters | Seaside · Monterey County | — | — |
| A Stupak Builders INC | Nathan Andrew Stupak | — | (626) 404 8210 | GC, remodel, ADU | West Covina · Los Angeles County | — | — |
| A Subcool Air Conditioning INC | Ararat Kh Esagholian | — | (818) 609 8776 | HVAC | Van Nuys · Los Angeles County | — | — |
| A Sunrise Construction | Hector Gonzalez | — | (818) 343 0654 | Other roofers | Reseda · Los Angeles County | — | — |
| A T A Fine Work Painting | Trejo Arteaga Armando | — | (760) 500 7062 | Windows, patio, painters | Vista · San Diego County | — | — |