diff --git a/src/boost/boost.go b/src/boost/boost.go
index 62d45a37..16df96ef 100644
--- a/src/boost/boost.go
+++ b/src/boost/boost.go
@@ -897,7 +897,7 @@ func AddFarmerToContract(client dc.Client, contract *Contract, guildID string, c
 					if el.GuildContractRole.ID != "" {
 						_ = client.AddGuildMemberRole(el.GuildID, b.UserID, el.GuildContractRole.ID)
 					}
-					if el.ChannelID != "" {
+					if contract.State != ContractStateSignup && el.ChannelID != "" {
 						_ = client.AddThreadMember(el.ChannelID, b.UserID)
 					}
 				}
@@ -1429,10 +1429,12 @@ func JoinContract(client dc.Client, guildID string, channelID string, userID str
 	// test if userID in Boosters
 	if contract.Boosters[userID] != nil {
 		contract.Boosters[userID].Ping = bell
-		for _, el := range contract.Location {
-			if (guildID == "" || el.GuildID == guildID) && dc.IsSnowflake(userID) {
-				if el.ChannelID != "" {
-					_ = client.AddThreadMember(el.ChannelID, userID)
+		if contract.State != ContractStateSignup {
+			for _, el := range contract.Location {
+				if (guildID == "" || el.GuildID == guildID) && dc.IsSnowflake(userID) {
+					if el.ChannelID != "" {
+						_ = client.AddThreadMember(el.ChannelID, userID)
+					}
 				}
 			}
 		}
@@ -1742,6 +1744,8 @@ func StartContractBoosting(client dc.Client, guildID string, channelID string, u
 
 	contract.enforceOnlyOneTokenTimeBooster()
 
+	AddBoostersToThread(client, contract)
+
 	if contract.Style&ContractFlagAMQP != 0 && len(contract.Location) > 0 {
 		guildID := contract.Location[0].GuildID
 		if guildID != "" {
diff --git a/src/boost/contract_test.go b/src/boost/contract_test.go
index 6cf839ce..505b90d9 100644
--- a/src/boost/contract_test.go
+++ b/src/boost/contract_test.go
@@ -808,6 +808,41 @@ func TestBoostMenuNextBoosterTokens(t *testing.T) {
 	}
 }
 
+func TestAddFarmerToContract_SignupDoesNotAddThreadMember(t *testing.T) {
+	client := dctest.New().
+		WithGuild("guild1", "Guild 1").
+		WithChannel("thread1", "guild1", "contract-thread").
+		WithUser("123456789012345678", "farmer1", "Farmer One")
+
+	contract := &Contract{
+		ContractHash: "test-hash-thread-signup",
+		ContractID:   "test-contract",
+		CoopID:       "test-coop",
+		CoopSize:     10,
+		State:        ContractStateSignup,
+		CreatorID:    []string{"creator1"},
+		Order:        make([]string, 0),
+		Boosters:     make(map[string]*Booster),
+		Location:     []*LocationData{{GuildID: "guild1", ChannelID: "thread1"}},
+	}
+	Contracts[contract.ContractHash] = contract
+	defer delete(Contracts, contract.ContractHash)
+
+	b, err := AddFarmerToContract(client, contract, "guild1", "thread1", "123456789012345678", ContractOrderSignup, false, false)
+	if err != nil {
+		t.Fatalf("unexpected error adding farmer: %v", err)
+	}
+	if b == nil {
+		t.Fatalf("expected booster to be created, got nil")
+	}
+
+	for _, call := range client.Calls {
+		if call.Method == "AddThreadMember" {
+			t.Errorf("unexpected AddThreadMember call in signup mode: %v", call)
+		}
+	}
+}
+
 func TestAddFarmerToContract_AddsThreadMember(t *testing.T) {
 	client := dctest.New().
 		WithGuild("guild1", "Guild 1").
@@ -863,6 +898,40 @@ func TestAddFarmerToContract_AddsThreadMember(t *testing.T) {
 	}
 }
 
+func TestJoinContract_SignupDoesNotAddThreadMember(t *testing.T) {
+	client := dctest.New().
+		WithGuild("guild1", "Guild 1").
+		WithChannel("thread2", "guild1", "signup-contract-thread").
+		WithUser("234567890123456789", "farmer2", "Farmer Two")
+
+	contract := &Contract{
+		ContractHash: "test-hash-signup-join",
+		ContractID:   "test-contract-signup",
+		CoopID:       "test-coop-signup",
+		CoopSize:     5,
+		State:        ContractStateSignup,
+		CreatorID:    []string{"creator1"},
+		Order:        []string{"creator1"},
+		Boosters: map[string]*Booster{
+			"creator1": {UserID: "creator1", Name: "Creator", Nick: "Creator"},
+		},
+		Location: []*LocationData{{GuildID: "guild1", ChannelID: "thread2"}},
+	}
+	Contracts[contract.ContractHash] = contract
+	defer delete(Contracts, contract.ContractHash)
+
+	err := JoinContract(client, "guild1", "thread2", "234567890123456789", false)
+	if err != nil {
+		t.Fatalf("unexpected error joining contract: %v", err)
+	}
+
+	for _, call := range client.Calls {
+		if call.Method == "AddThreadMember" {
+			t.Errorf("unexpected AddThreadMember call on signup join: %v", call)
+		}
+	}
+}
+
 func TestJoinRunningContract_AddsThreadMember(t *testing.T) {
 	client := dctest.New().
 		WithGuild("guild1", "Guild 1").
@@ -905,6 +974,57 @@ func TestJoinRunningContract_AddsThreadMember(t *testing.T) {
 	}
 }
 
+func TestStartContractBoosting_AddsBoostersToThread(t *testing.T) {
+	client := dctest.New().
+		WithGuild("guild1", "Guild 1").
+		WithChannel("thread3", "guild1", "contract-thread-3").
+		WithUser("111111111111111111", "creator1", "Creator").
+		WithUser("222222222222222222", "farmer1", "Farmer One").
+		WithUser("333333333333333333", "farmer2", "Farmer Two")
+
+	contract := &Contract{
+		ContractHash: "test-hash-start-boosting",
+		ContractID:   "test-contract",
+		CoopID:       "test-coop",
+		CoopSize:     5,
+		State:        ContractStateSignup,
+		Style:        ContractStyleFastrun,
+		CreatorID:    []string{"111111111111111111"},
+		Order:        []string{"111111111111111111", "222222222222222222", "333333333333333333"},
+		Boosters: map[string]*Booster{
+			"111111111111111111": {UserID: "111111111111111111", Name: "Creator", Nick: "Creator"},
+			"222222222222222222": {UserID: "222222222222222222", Name: "Farmer1", Nick: "Farmer1"},
+			"333333333333333333": {UserID: "333333333333333333", Name: "Farmer2", Nick: "Farmer2"},
+		},
+		Location: []*LocationData{{GuildID: "guild1", ChannelID: "thread3", ListMsgID: "msg1"}},
+	}
+	Contracts[contract.ContractHash] = contract
+	defer delete(Contracts, contract.ContractHash)
+
+	err := StartContractBoosting(client, "guild1", "thread3", "111111111111111111")
+	if err != nil {
+		t.Fatalf("unexpected error starting contract: %v", err)
+	}
+
+	if contract.State != ContractStateFastrun {
+		t.Fatalf("expected contract state to be Fastrun, got %d", contract.State)
+	}
+
+	// Verify all 3 users were added to thread3
+	addedUsers := make(map[string]bool)
+	for _, call := range client.Calls {
+		if call.Method == "AddThreadMember" && len(call.Args) >= 2 && call.Args[0] == "thread3" {
+			addedUsers[call.Args[1]] = true
+		}
+	}
+
+	for _, uid := range []string{"111111111111111111", "222222222222222222", "333333333333333333"} {
+		if !addedUsers[uid] {
+			t.Errorf("expected user %s to be added to thread3, calls: %v", uid, client.Calls)
+		}
+	}
+}
+
 func TestRefreshBoostListMessage_EmptyMsgIDs(t *testing.T) {
 	client := dctest.New().
 		WithGuild("guild1", "Guild 1").
diff --git a/src/boost/thread.go b/src/boost/thread.go
index 8a523ed0..302bdacc 100644
--- a/src/boost/thread.go
+++ b/src/boost/thread.go
@@ -6,9 +6,33 @@ import (
 	"strings"
 	"time"
 
+	"github.com/mkmccarty/TokenTimeBoostBot/src/config"
 	"github.com/mkmccarty/TokenTimeBoostBot/src/dc"
 )
 
+// AddBoostersToThread adds all contract boosters and creators to the contract thread(s)
+// when the contract is not in signup mode.
+func AddBoostersToThread(client dc.Client, contract *Contract) {
+	if client == nil || contract == nil || contract.State == ContractStateSignup {
+		return
+	}
+	for _, el := range contract.Location {
+		if el == nil || el.ChannelID == "" {
+			continue
+		}
+		for userID := range contract.Boosters {
+			if dc.IsSnowflake(userID) {
+				_ = client.AddThreadMember(el.ChannelID, userID)
+			}
+		}
+		for _, creatorID := range contract.CreatorID {
+			if dc.IsSnowflake(creatorID) && creatorID != config.DiscordAppID {
+				_ = client.AddThreadMember(el.ChannelID, creatorID)
+			}
+		}
+	}
+}
+
 // GetSlashRenameThread is the definition of the slash command
 func GetSlashRenameThread(cmd string) *dc.Command {
 	command := guildOnlyCommand(cmd, "Rename Boost Bot created contract thread.")