diff --git a/include/cantera/thermo/ThermoPhase.h b/include/cantera/thermo/ThermoPhase.h
index 55bdd0d0ab..f93b16cd78 100644
--- a/include/cantera/thermo/ThermoPhase.h
+++ b/include/cantera/thermo/ThermoPhase.h
@@ -1097,6 +1097,96 @@ class ThermoPhase : public Phase
      */
     virtual void setState_SV(doublereal s, doublereal v, doublereal tol = 1.e-4);
 
+    //! Set the density (kg/m**3) and pressure (Pa) at constant
+    //! composition
+    /*!
+     *  This method must be reimplemented in derived classes, where it
+     *   may involve the solution of a nonlinear equation. Within %Cantera,
+     *   the independent variable is the density. Therefore, this function
+     *   solves for the temperature that will yield the desired input pressure
+     *   and density. The composition is held constant during this process.
+     *
+     *  This base class function will print an error, if not overwritten.
+     *
+     *  @param rho Density (kg/m^3)
+     *  @param p   Pressure (Pa)
+     */
+    virtual void setState_RP(doublereal rho, doublereal p){
+        throw NotImplementedError("ThermoPhase::setState_RP");
+    }
+
+    //! Set the density (kg/m**3), pressure (Pa) and mole fractions
+    /*!
+     * Note, the mole fractions are set first before the density and pressure
+     * are set. Setting the pressure may involve the solution of a nonlinear equation.
+     *
+     * @param rho  Density (kg/m^3)
+     * @param p    Pressure (Pa)
+     * @param x    Vector of mole fractions.
+     *             Length is equal to m_kk.
+     */
+    virtual void setState_RPX(doublereal rho, doublereal p, const doublereal* x);
+
+    //! Set the density (kg/m**3), pressure (Pa) and mole fractions
+    /*!
+     * Note, the mole fractions are set first before the density and pressure
+     * are set. Setting the pressure may involve the solution of a nonlinear equation.
+     *
+     *  @param rho  Density (kg/m^3)
+     *  @param p    Pressure (Pa)
+     *  @param x    Composition map of mole fractions. Species not in
+     *              the composition map are assumed to have zero mole fraction
+     */
+    virtual void setState_RPX(doublereal rho, doublereal p, const compositionMap& x);
+
+    //! Set the density (kg/m**3), pressure (Pa) and mole fractions
+    /*!
+     * Note, the mole fractions are set first before the density and pressure
+     * are set. Setting the pressure may involve the solution of a nonlinear equation.
+     *
+     *  @param rho  Density (kg/m^3)
+     *  @param p    Pressure (Pa)
+     *  @param x    String containing a composition map of the mole fractions. Species not in
+     *              the composition map are assumed to have zero mole fraction
+     */
+    virtual void setState_RPX(doublereal rho, doublereal p, const std::string& x);
+
+    //! Set the density (kg/m**3), pressure (Pa) and mass fractions
+    /*!
+     * Note, the mass fractions are set first before the density and pressure
+     * are set. Setting the pressure may involve the solution of a nonlinear equation.
+     *
+     *  @param rho  Density (kg/m^3)
+     *  @param p    Pressure (Pa)
+     *  @param y    Vector of mole fractions.
+     *              Length is equal to m_kk.
+     */
+    virtual void setState_RPY(doublereal rho, doublereal p, const doublereal* y);
+
+    //! Set the density (kg/m**3), pressure (Pa) and mass fractions
+    /*!
+     * Note, the mass fractions are set first before the density and pressure
+     * are set. Setting the pressure may involve the solution of a nonlinear equation.
+     *
+     *  @param rho Density (kg/m^3)
+     *  @param p   Pressure (Pa)
+     *  @param y   Composition map of mole fractions. Species not in
+     *             the composition map are assumed to have zero mole fraction
+     */
+    virtual void setState_RPY(doublereal rho, doublereal p, const compositionMap& y);
+
+    //! Set the density (kg/m**3), pressure (Pa) and mass fractions
+    /*!
+     * Note, the mass fractions are set first before the density and pressure
+     * are set. Setting the pressure may involve the solution of a nonlinear equation.
+     *
+     *  @param rho  Density (kg/m^3)
+     *  @param p    Pressure (Pa)
+     *  @param y    String containing a composition map of the mole fractions. Species not in
+     *              the composition map are assumed to have zero mole fraction
+     */
+    virtual void setState_RPY(doublereal rho, doublereal p, const std::string& y);
+
     //@}
 
 private:
diff --git a/src/thermo/ThermoPhase.cpp b/src/thermo/ThermoPhase.cpp
index b24282630a..56a05bfce1 100644
--- a/src/thermo/ThermoPhase.cpp
+++ b/src/thermo/ThermoPhase.cpp
@@ -180,6 +180,42 @@ void ThermoPhase::setState_TP(doublereal t, doublereal p)
     setPressure(p);
 }
 
+void ThermoPhase::setState_RPX(doublereal rho, doublereal p, const doublereal* x)
+{
+        setMoleFractions(x);
+        setState_RP(rho, p);
+}
+
+void ThermoPhase::setState_RPX(doublereal rho, doublereal p, const compositionMap& x)
+{
+    setMoleFractionsByName(x);
+    setState_RP(rho,p);
+}
+
+void ThermoPhase::setState_RPX(doublereal rho, doublereal p, const std::string& x)
+{
+    setMoleFractionsByName(x);
+    setState_RP(rho,p);
+}
+
+void ThermoPhase::setState_RPY(doublereal rho, doublereal p, const doublereal* y)
+{
+    setMassFractions(y);
+    setState_RP(rho,p);
+}
+
+void ThermoPhase::setState_RPY(doublereal rho, doublereal p, const compositionMap& y)
+{
+    setMassFractionsByName(y);
+    setState_RP(rho,p);
+}
+
+void ThermoPhase::setState_RPY(doublereal rho, doublereal p, const std::string& y)
+{
+    setMassFractionsByName(y);
+    setState_RP(rho,p);
+}
+
 void ThermoPhase::setState_PX(doublereal p, doublereal* x)
 {
     setMoleFractions(x);