The　Leaning　Tower　of　Pisa　was　built　between　1173　and　1360　and　began　to　lean　at　the　beginning　of　its　construction.　Extensive　investigations　to　reveal　the　causes　of　the　tilting　only　began　in　the　early　20th　century.　Although　few　earthquakes　have　been　recorded,　there　is　a　renewed　interest　in　the　seismic　behavior　of　the　tower　triggered　by　the　availability　of　new　data　and　technologies.　This　paper　highlights　the　influence　of　using　new　strength-controlled　constitutive　models　in　case　of　1D　nonlinear　response　analysis.　This　is　an　aspect　that　has　been　poorly　investigated.　Most　of　the　computer　codes　currently　available　for　nonlinear　seismic　response　analysis　(SRA)　of　soil　use　constitutive　models　able　to　capture　small-strain　behavior,　but　the　large-strain　shear　strength　is　left　uncontrolled.　This　can　significantly　affect　the　assessment　of　a　1-D　response　analysis　and　the　Leaning　Tower’s　subsoil　can　be　useful　for　this　study　as　it　represents　a　well-documented　and　well-characterized　site.　After　a　geological　and　geotechnical　description　of　the　subsoil　profile　and　a　synthesis　of　available　data,　the　seismic　input　is　defined.　One-dimensional　SRAs　were　carried　out　by　means　of　a　computer　code　which　considers　an　equivalent-linear　soil　modelling　and　two　codes　which　assume　nonlinear　soil　response　and　permit　to　use　strength-controlled　constitutive　models.　All　the　parameters　were　calibrated　on　the　basis　of　the　same　soil　data,　therefore　allowing　for　a　direct　comparison　of　the　results.　©　2018　by　the　authors.　Licensee　MDPI,　Basel,　Switzerland.