diff --git a/gtsam/base/ThreadsafeException.h b/gtsam/base/ThreadsafeException.h
index 652dbd90f..ad228e590 100644
--- a/gtsam/base/ThreadsafeException.h
+++ b/gtsam/base/ThreadsafeException.h
@@ -26,6 +26,7 @@
 #include <string>
 #include <typeinfo>
 #include <exception>
+#include <optional>
 
 #ifdef GTSAM_USE_TBB
 #include <tbb/tbb_allocator.h>
@@ -53,7 +54,7 @@ protected:
 
 protected:
   bool dynamic_; ///< Whether this object was moved
-  mutable boost::optional<String> description_; ///< Optional description
+  mutable std::optional<String> description_; ///< Optional description
 
   /// Default constructor is protected - may only be created from derived classes
   ThreadsafeException() :
diff --git a/gtsam/discrete/DecisionTree-inl.h b/gtsam/discrete/DecisionTree-inl.h
index 9f3d5e8f9..0726da3dd 100644
--- a/gtsam/discrete/DecisionTree-inl.h
+++ b/gtsam/discrete/DecisionTree-inl.h
@@ -24,7 +24,6 @@
 #include <algorithm>
 #include <boost/format.hpp>
 #include <boost/make_shared.hpp>
-#include <boost/optional.hpp>
 
 #include <cmath>
 #include <fstream>
@@ -34,6 +33,7 @@
 #include <sstream>
 #include <string>
 #include <vector>
+#include <optional>
 
 namespace gtsam {
 
@@ -563,7 +563,7 @@ namespace gtsam {
   typename DecisionTree<L, Y>::NodePtr DecisionTree<L, Y>::compose(
       Iterator begin, Iterator end, const L& label) const {
     // find highest label among branches
-    boost::optional<L> highestLabel;
+    std::optional<L> highestLabel;
     size_t nrChoices = 0;
     for (Iterator it = begin; it != end; it++) {
       if (it->root_->isLeaf())
@@ -571,7 +571,7 @@ namespace gtsam {
       boost::shared_ptr<const Choice> c =
           boost::dynamic_pointer_cast<const Choice>(it->root_);
       if (!highestLabel || c->label() > *highestLabel) {
-        highestLabel.reset(c->label());
+        highestLabel = c->label();
         nrChoices = c->nrChoices();
       }
     }
diff --git a/gtsam/discrete/Signature.cpp b/gtsam/discrete/Signature.cpp
index 146555898..bc045e8c2 100644
--- a/gtsam/discrete/Signature.cpp
+++ b/gtsam/discrete/Signature.cpp
@@ -137,14 +137,14 @@ namespace gtsam {
   }
 
   Signature& Signature::operator=(const string& spec) {
-    spec_.reset(spec);
+    spec_ = spec;
     Table table;
     parser::It f = spec.begin(), l = spec.end();
     bool success =
         qi::phrase_parse(f, l, parser::grammar.table, qi::space, table);
     if (success) {
       for (Row& row : table) normalize(row);
-      table_.reset(table);
+      table_ = table;
     }
     return *this;
   }
@@ -153,7 +153,7 @@ namespace gtsam {
     Table table = t;
     for(Row& row: table)
       normalize(row);
-    table_.reset(table);
+    table_ = table;
     return *this;
   }
 
diff --git a/gtsam/discrete/Signature.h b/gtsam/discrete/Signature.h
index 3138435a9..963843ab2 100644
--- a/gtsam/discrete/Signature.h
+++ b/gtsam/discrete/Signature.h
@@ -19,7 +19,7 @@
 #pragma once
 #include <string>
 #include <vector>
-#include <boost/optional.hpp>
+#include <optional>
 #include <gtsam/discrete/DiscreteKey.h>
 
 namespace gtsam {
@@ -68,10 +68,10 @@ namespace gtsam {
     DiscreteKeys parents_;
 
     // the given CPT specification string
-    boost::optional<std::string> spec_;
+    std::optional<std::string> spec_;
 
     // the CPT as parsed, if successful
-    boost::optional<Table> table_;
+    std::optional<Table> table_;
 
   public:
    /**
@@ -124,7 +124,7 @@ namespace gtsam {
    KeyVector indices() const;
 
    // the CPT as parsed, if successful
-   const boost::optional<Table>& table() const { return table_; }
+   const std::optional<Table>& table() const { return table_; }
 
    // the CPT as a vector of doubles, with key's values most rapidly changing
    std::vector<double> cpt() const;