Taking the main road
 
During its early years (1948-1956), ISA was engaged in shaping commanding, organizational, managerial, and operational policies. At the same time, ISA searched and identified targets, studied and developed its Modus Operandi, and put it to the test.
This period was characterized by lack of knowledge and experience since there was no one to learn from; and so, the founding generation, directed by Isser Harel and later, Yitzhak (Izi) Dorot had no alternative but to rely mainly on gut feeling and common sense when facing problems. Due to the circumstances, events, the general mood which prevailed at the newly risen State, and the need to ensure Israel's existence and protect it from enemies and rivals from within and without, ISA turned into "the Big Brother" whose eye watches everyone.
During the second decade ISA took the main road. Since the Kastner Affair in 1957, ISA sallied forth from its anonymity and was subject to criticism, parliamentary control, and a strong public criticism.
Under the command of Amos Manor (1953-1963), third ISA Director, and later on, Yossef Harmelin (1964-1974), ISA was instructed to focus especially on its security-thwarting activity. As time passed, ISA managed to cope with the difficulties encountered and was released from a wide range of "non security" tasks. ISA was forced to deal with these tasks since the government was unable to solve certain problems such as: fighting the "black market", assisting the Israel Tax Authority to track down tax evaders, preventing smuggling from abroad, preventing missionary activity, assisting the police to prevent riots based on communal affiliation etc. After these tasks were dealt by other governmental institutions, ISA's activity in the above mentioned issues was completely cancelled.

 
Establishing a doctrine
During the second decade, ISA operated as an institutionalized organization with clear cut tasks, a defined structure, and even began establishing a devised doctrine and operated less according to a "trial and error" method.
Towards the end of 1956, ISA's cooperation with the IDF was prominent during the Sinai War (1956) in tracing and arresting suspects in terrorist activity (infiltrators, Fedayeen, and spies on behalf of the Egyptian Intelligence), and supervising Gaza Strip residents until the retreat from the Sinai Peninsula.
As the number of routine and unique tasks increased, so did the standards, and budget. ISA's manpower consisted of about 600 employees nationwide at the HQ and various Field Offices. Its employees coped with different tasks (not necessarily according to order of importance since everything was important at the time…), some of them included:

Assisting the Israeli military government
Following the War of Independence (1948), there were three major Arab populations dispersed in different areas: the Galilee, the Triangle (in Arabic: al-Muthalath), and the Negev. The military government enabled the use of emergency ordinances and monitored the activities of the populations near the Green Line.
ISA served as the Intelligence officer for the military government until the military government's annulment in 1966. ISA carried out security and lie detector checks and provided its expertise regarding issuing movement permits for Arabs from one area to another in Israeli territory, providing business licenses, passing certificates for those who wish to exit or return to and from Arab countries through the crossing points, and certificates for family reunifications.
In addition, ISA gathered information about the mood among Palestinians and reported the information to elements in the government, police and army. Moreover, ISA passed threat warnings about riots and plans to carry out violent demonstrations. This activity was conducted until 1967 by only 11 area case officers (Intelligence persons who maintain contact with sources and direct them); most of them were former Intelligence Service veterans and former Haganah members who made use of their fluent Arabic and knowledge of local traditions.

Thwarting Political Subversion
The Israeli Communist Party (ICP) influenced by the U.S.S.R encouraged anti-Zionist activity by supporting Arab nationalism. The party's platform called to acknowledge the Palestinians' right for "self-determination until independence" and the demand for the refugees' right of return to their "country".
The Communists – operating in small and scattered cells – incited people to ostracize the Israeli elections in 1955 and carry out violent protests such as the protest in Nazareth on May 1, 1958. The number of ICP voters increased at every election. Apart from its overt activity, ICP also conducted clandestine activity which included infiltration of its people into different bodies for Intelligence reconnaissance and incitement. In addition, in 1959 former ICP activists established a radical and national movement called Al Ard (in Arabic: the land). This movement took advantage of the freedom of expression for propaganda ─ a basic right in Israel – and encouraged Jihadi activity.
The movement was outlawed under the order (November 23, 1964) published by the Minister of Defense in the documents that designated Al Ard movement as "an illegal organization". In 1965, the election committee disqualified the movement's nominal list for the Knesset (the Israeli Parliament), and the Israeli High Court of Justice rejected the movement's appeal. The court's ruling stated that the movement's members "do not acknowledge the state of Israel and deny its existence…" and that "the movement (Al Ard) endangers the Israeli democracy while taking advantage of democratic procedures in order to destroy it."

Thwarting Arab espionage
Since their defeat in the War of Independence, Arab countries have made unflagging attempts to obtain information on Israel in military, economic, political, scientific, and social domains.
Arab countries recruited agents who infiltrated into Israel under cover; for example under covered as new immigrants. The links with the agents was conducted using encrypted transmissions (radio or Mors), coded written dispatches (by mail or by messengers) or written dispatches in clandestine ink, and DLB ((Dead Letter Box – a mean of clandestine communications enabling no direct connection between the parties. The connection is made by concealing an object/a dispatch/money in a designated spot and then emptying it, keeping a separation between the parties. The dropping is done clandestinely).

ISA studied rival Modus Operandi and managed to expose many agents. Some of them include:
• Avri Elad (The Third Man) ─ arrested in 1957, surrendered the Jewish network operating in Egypt to the Egyptian Intelligence Services.
• Kiborak Yaccobian ─ infiltrated into Israel from Egypt in 1961 under false identity.
• Shmu'el Sami Baruch ─ an Israeli-Jewish businessman who volunteered to the Egyptian Intelligence in 1963.
• Mordechai Luk (Man in Trunk) who out of his own free will joined the Egyptian Intelligence Services in 1961 and in 1964 was exposed in Rome while the Egyptians attempted to kidnap him to Cairo.

   Some of the agents exposed were "doubled". One of them operated before the Six Day War (June 1967) in a grand strategic and tactical Intelligence operation which greatly assisted the IDF in bringing about its stun blow.

Thwarting Eastern European and Western Espionage
The Cold War between the West and the Eastern Communist Bloc directed by the former U.S.S.R in this decade, affected Israel and the latter became the focus point to both parties. The Eastern Communist countries considered Israel as an American satellite country and gathered Intelligence and technological information concerning Israel. This information was intended to be used for their general needs, including the wish to expand Soviet influence in the Middle East by gathering Intelligence on IDF and delivering it to Arab elements.
The Soviet Union considered many Israelis who immigrated from Eastern Europe a recruitment pool to be used. Israel was overrun with many insurgents; some were recruited under pressure and threats and were operated by clandestine Intelligence stations located within embassies in Eastern Europe which enjoyed diplomatic immunity and were considered to be sophisticated, experienced, and difficult rivals.
ISA reinforced strict surveillance on Eastern European Intelligence activity in order to deal with this issue, shadowed foreign handlers who arrived to Israel to meet with their agents, exposed a considerable amount of them and carried out duping operations vis à vis rivals. In addition, ISA conducted many interviews for new Eastern European immigrants to trace those who worked for foreign Intelligence services.

Some of the agents exposed in the second decade included:
• Ze'ev Avni – an employee of the Israeli Foreign Ministry, was exposed as a Soviet agent in 1956.
• A'haron Cohen – an Orientalist and a Kibbutz member who was exposed in 1958 while making contact with a Soviet Intelligence officer.
• Levi Levi – an ISA employee who was exposed as a Polish agent in 1958.
• Israel Bar – a former IDF Lieutenant Colonel, arrested as a Soviet agent in 1961.
• Kurt Sita – a scientist at the Institute of technology, arrested in 1960 after working for the Czech Intelligence services.
• E.S – a Romanian Intelligence agent, captured in 1965 while receiving a radio transmission from Bucharest with his headset on.

Western countries also showed great interest in Israel and their Intelligence services tried to make out of Israel's political-strategic and military-operational plans, as well as monitor Israel's technological development. This was another obstacle and ISA managed to deal with it in creative ways.

Thwarting subversion from radical Jewish right and left wing elements
Through out this decade, left and right wing radical elements posed danger for Israel's security and democracy.
Radical left wing elements – various anti-Zionist factions were identified in the 60s such as the ISO (Israeli Socialist Organization) which later on was called The Matzpen, the name of their journal (in Hebrew: the compass). Until 1967, the Matzpen conducted little activity, but due to the Six Day War outcomes (June 1967) a significant change occurred in the pattern and range of the Matzpen's activity; thus, calling for special attention on behalf of ISA.
 Members in these organizations were usually young, educated, and intelligent anarchists who believed their way to be the righteous one and were willing to dedicate all their energy and time. It was not easy to infiltrate into these organizations and ISA had to trace and improvise alternative solutions which happened to be successful.
At the same time, ISA continued to monitor organizations such as ICP (Israeli Communist Party), Rakah (New Communist List), various Fronts, pacifistic and Trozky-affiliated movements etc.

Radical right wing elements – the activity of national and religious underground movements decreased unlike the first decade. Some of these movements included The National Front, Brit Hakanaim (in Hebrew: Covenant of the Zealots), Mahteret Tzrifin (in Hebrew: Tzrifin Underground), Malchut Yisrael (in Hebrew: Kingdom of Israel), and the violent underground activity against the reparations from Germany.
The Kastner Affair was the last founding event and from there until 1967, no other underground movements were discovered. This decade is characterized as the Golden Age of Israeli democracy with no illegal or violent subversive activity. However, one such unusual event was the kidnap of Yossele Schumacher by his radical-fanatic-religious grandfather and his rescue in 1962 in a joint ISIS-ISA operation, after the Israeli police failed to trace him. In this case, ISA managed to infiltrate into radical, religious and anti-Zionist circles considered to be a national mission intended to prevent a brothers' war between religious and non religious Jews.

Collecting Intelligence
Since its establishment, ISA has been one of the primary Israeli Intelligence gathering agencies. The Intelligence gathered using operational Modus Operandi serve the Intelligence community on a routine basis and while at emergency; especially at times of tension, high alertness due to events on the border line, security events etc.
In the second decade, much activity has been done in this domain, mainly in the period prior to the Six Day War. For example, thanks to interviews conducted to new immigrants who served in the militaries of the Warsaw Pact; much Intelligence was delivered to IDF regarding Soviet-made weapons supplied to Arab militaries which assisted IDF in tackling the issue.

Security
The issue of security focused only on three domains:
Physical security ─ buildings such as essential strategic facilities and governmental institutions are guarded using an array of security officers directed by ISA.
Data protection – meticulous interviews conducted to candidates for classified roles.
VIP protection – David Ben-Gurion, first Israeli PM, was the sole VIP who received protection but after a hand-grenade exploded at the Knesset (the Israeli parliament) in October 1957 resulting in several injured ministers, the Knesset guard was established, and more VIPs received protection.

Operational assistance
In the second decade, ISA already operated a very sophisticated and a skilled operations unit that gained much experience and constantly developed advanced working methods while at the same time received technological support. ISA was awarded the Israel Defense Prize in 1966, the first time ever for one of its technological breakthroughs that brought ISA the most notable operational achievements.
  It should be mentioned that up to 1963, ISA operations unit worked both in Israel and abroad while at the same time ISA operational unit personnel operated for ISIS as well, before ISIS established such unit. A prominent such example was the kidnapping operation of the Nazi Adolf Eichmann in Argentina to be judged in an Israeli court.

Summary
 The period of 1957-1967 before the Six Day War was characterized by an intensive activity in various areas. And so, ISA was able to prepare itself for future events in the next decade.