| Kate Winslet | Detective Mare Sheehan |
| Julianne Nicholson | Lori Ross |
| Jean Smart | Helen Fahey |
| Angourie Rice | Siobhan Sheehan |
| Evan Peters | Colin Zabel |
| Sosie Bacon | Carrie Layden |
| David Denman | Frank Sheehan |
| Neal Huff | Father Dan Hastings |
| James McArdle | Deacon Mark Burton |
| Guy Pearce | Richard Ryan |
| Cailee Spaeny | Erin McMenamin |
| John Douglas Thompson | Chief Carter |
| Joe Tippett | John Ross |
| Kate Arrington | Faye |
| Ruby Cruz | Jess Riley |
| Enid Graham | Dawn Bailey |
| Cameron Mann | Ryan Ross |
| Jack Mulhern | Dylan Hinchey |
| Patrick Murney | Kenny McMenamin |
| Chinasa Ogbuagu | Beth Hanlon |
| Phyllis Somerville | Betty Carroll |
| Robbie Tann | Billy Ross |
| Madeline Weinstein | Becca |
| Izzy King | Drew Sheehan |
| Mackenzie Lansing | Brianna Delrasso |
| Connie Giordano | Patty Delrasso |
| Eric T. Miller | Tony Delrasso |
| Katie Kreisler | Trisha Riley |
| Vanita Kalra | Dr. Christine Long |
| Kassie Mundhenk | Moira Ross |
| Patrick McDade | Glen Carroll
(as Patrick F. McDade) |
| Drew Scheid | Geoff Gabeheart |
| Anthony Norman | Nathan Forde |
| Brian Rock | Katie's Uncle |
| Lauren Pilgermayer | Server |
| Patsy Meck | Jan Kelly |
| Justin Hurtt-Dunkley | Officer Trammel |
| Kittson O'Neill | Officer Susie Holbert |
| Pat DeFusco | Officer Tommy Boyle |
| Brian Gallagher | Corporal Jimmy Masterson |
| Katie Meginniss | Book Signing Guest |
| Hannah Flannery | Shannon |
| Caroline Mixon | Kerry |
| Meredith Sullivan | Kylie |
| Rachel Poletick | Kelly |
| Sadat Waddy | Sean |
| Joey Blanco | Teen Boy at Party |
| Jared Michael Delaney | Reporter |
| Brooke Stacy Mills | Reporter |
| Jeremy Gabriel | Steve Hinchey |
| Debbie Campbell | Katherine Hinchey |
| Cody N. Carter | Valet
(as Cody Carter) |
| Gabi Faye | Brianna's Friend |
| Robert L. Anderson III | Church Goer
(uncredited) |
| Gary Ayash | Neighbor
(uncredited) |
| David Baker | Church member
(uncredited) |
| Kevin D. Benton | Bar Patron
(uncredited) |
| Zack Beyer | Bartender
(uncredited) |
| Setty Brosevelt | Protesting Neighbor
(uncredited) |
| Chris Bruno | Tony Del Rasso
(uncredited) |
| Jennifer Butler | Sheehan Neighbor
(uncredited) |
| Jimmy Chang | Church Attendee
(uncredited) |
| Savannah Rae Dillon | Country Club Woman
(uncredited) |
| Bella Dontine | Reporter
(uncredited) |
| James Dormuth | Church Goer
(uncredited) |
| Harold G. Eder II | Activist
(uncredited) |
| Dave Ferrier | Church Goer
(uncredited) |
| Cory Kastle | Church Goer
(uncredited) |
| Alphonso Kennish | Town Member
(uncredited) |
| R.J. Koker | Church Goer
(uncredited) |
| Lamar Kukuk | Book Signing Guest
(uncredited) |
| John Xavier Lambert | Beth's Kid (son)
(uncredited) |
| Debbie Lay | Neighbor
(uncredited) |
| Chelsea Marie Marlowe | Academy Student
(uncredited) |
| John Martineau | Waiter
(uncredited) |
| Andrew McKeough | Neighbor
(uncredited) |
| Catherine Mary Moroney | Church Goer
(uncredited) |
| Jeffrey Mowery | Carroll's Neighbor
(uncredited) |
| Laura Jill Newman | Basketball Team Member
(uncredited) |
| Damien Paige | Church Goer
(uncredited) |
| Misha Pharaone | Country Club Member
(uncredited) |
| Madeline Poeta | Restaurant Patron
(uncredited) |
| Chuck Pressler | Paramedic
(uncredited) |
| Tatiana Romero | Beth's Kid
(uncredited) |
| Liz Sanford | Churchgoer
(uncredited) |
| Daniel Sassa | Church Member
(uncredited) |
| William G. Tomek | Church Attendee
(uncredited) |
| Scott Vogel | Book Signing Attendee
(uncredited) |