Spring - erro no start do tomcat

Boa Tarde, Pessoal!

Hoje comecei a estudar o framework Spring e estou tendo um pouco de dificuldade em montar o ambiente. Vários erros eu já consegui resolver colocando os jars necessários, porém tem um que não estou conseguindo. Continuarei pesquisando, mais se alguem puder me ajudar.

Erro no start no tomcat7:

Grave: Context initialization failed
java.lang.NoClassDefFoundError: org/springframework/beans/factory/config/BeanExpressionResolver
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
at java.lang.Class.getConstructor0(Unknown Source)
at java.lang.Class.getDeclaredConstructor(Unknown Source)
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:78)
at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:249)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:199)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:45)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4521)
at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5004)
at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:4999)
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: org.springframework.beans.factory.config.BeanExpressionResolver
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1643)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1488)
… 16 more

Agradeço desde já!